People also liked:
Intro / Spec / Review / FAQ / Manual / Video / Photo

Lvbu KF Series Ebike Kit

Only one cable connection
Super Easy to fit without special tools

Smart Asssit system / High Efficient Output Arrangement / Assist Range upto 90KM / Bluetooth 5.0 / Induction cut off system / Built in Gyroscope / Road Slope degrees detection / All Terrain Application / Anti-theft tracking

  • (optional)
  • (optional)
  • Smart ebike kit

    Fast installation in 5 minutes

  • 16-29 inch

    Multiple wheel size

  • Bluetooth 5.0

    A new era of interactive experience

  • Speed ≤32km/h

    250/350W high speed permanent magnet motor

  • Micro Power

    Provides you the best cycling experience

  • Four control ways

    Cadence/Auto/Manual/Torque

Product Specifications

    Model
    KF30S
    Battery Capacity
    36V 9Ah
    Cell Quantity
    30 cells
    Charging time
    4.5 H
    Battery Type
    18650 power lithium ion battery
    Charger
    AC110V-AC220V, DC42V 2A, Type C plug
    Assist Range
    90km

    *The assist range is under conditions: 60kg weight rider, ouside temperature 25℃,no wind, 50% assist level under manual mode, tires with enough air pressure, riding on flat level road.

    Top Speed
    32km/h
    Wheel size
    12"/14"/16"/20"/24"/26"/27.5"/28"/29"/700c
    Rated Power
    250W
    Motor Structure
    Gear drive
    Motor Efficiency
    >80%
    Max Torque
    30N.m
    Wireless Connection
    Bluetooth 5.0 (Allows the controller to connect to multiple devices at the same time)
    Product Dimensions
    Motor Weight
    2.6kg/2.55kg/3.25kg/3.45kg/2.7kg (250w Front / 250w Rear/350w Front/350w Rear/ 250w Rear with torque sensor)
    Battery Weight
    1.74 kg
    Controller Weight
    0.4 kg
    Package
    10kg, 70*70*20cm

Just 2 steps to convert a normal bike into a smart ebike

The KF series ebike kit can be quickly installed on your bike. It can be installed by anyone in a few minutes. There are two simple steps to turn your normal bike into a smart ebike:

INSTALLATION REQUIREMENTS

Fits Every Size Of Bike

KF series electric bicycle kit fits all standard bikes. It has multiple sizes from 16" to 29" and 700C

High quality 18650 lithium battery

EV lithium-ion battery cell with internal resistance as low as 18mΩ, capacity of 2900mA, 3C high-rate discharge.The 18650 power lithium battery offers consistency, high energy density, and faster charge-discharge performance.
Tried and tested over time, 80% capacity remains after 1000 cycles.

Using high-performance and high-safety BMS battery protection system

  • Over-discharge protection
  • Over current protection
  • Temperature protection
  • Over charge protection
  • Short circuit protection
  • Battery balance

250-500W high speed brushless motor

Small size, light weight, high efficiency, smooth operation, long life
Planetary gear and clutch: no resistance, easy to ride even when the battery is dead.

Rated power:  250W/350W
Peak power:  500W
Voltage:  36
Structure:  Gear Drive
Efficiency:  >80%
Max torque:  35-40N.m
Top speed:  32km/h

ARM Cortex-M3 main chip

with 6-axis gyroscope motion processing chip
configure Bluetooth 5.0 Moduel
6 high-sensitivity speed-measuring magnets for precise speed measurement

Micro Power System

10 years of research and development has gone into creating a versatile and cost-effective product for cyclists.
The micro power system offers intelligent assistance with induction brakes that have a response time of 10ms.
The system can sense the speed, acceleration and road slope,
it will help you automatically when you pedal.Uphill automatically increase power,downhill automatically cut off power.

5.0 Intelligent bluetooth connection

Bluetooth 5.0 module allows you to connect multiple devices at the same time

5 Smart Assist Modes

Thanks to the advanced algorithm, you can ride it naturally without any jerky and laggy, just like the electric assist is a part of you. It will work in tune with your pace. And we will keep on optimizing the system and publishing it from time to time. You will be able to update the system via the APP.

  • Leisure mode
  • Commute mode
  • Exercise mode
  • Manual mode
  • Climbing mode

Check the real time cycling data
and set the assist mode on the APP

And also you can check the speed, temperature, power, mileage, etc.

  • Real-time data
  • Riding speed
  • Battery
  • Temp
  • Mileage
  • Lock
  • Assist mode
  • Devices

Speed up to 32km/h

Speed limitation is settable in the APP.
*The default Speed limitation is 25km/h, you can set the speed limitation up to 32km/h in the APP.

Anti-theft tracking,lost bike tracking. You can report lost when your bike is stolen.

After you report lost, once the thief tried to connect the wheel with the APP, the system will locate the mobile phone, disable the motor immediately and upload the information to the server.

IP65 waterproof

IP65 waterproof grade makes you ride freely in the rain.

Multifunction bottle battery

  • Powder coating finish

    More durable and stronger than painting,
    not easy to scratch

  • Extra fix point to hold the battery firmly

    New snap function between controller and battery,
    The battery holder can clip the handle of the battery
    and makes the battery stay in the holder firmly

  • Hidden lock

    The battery lock is located directly under the controller
    which is safe and concealed

  • Brand new Type-C charging

    The Type-C charge and discharge port

High quality rim, skilled wheel truing process

High-quality carbon steel spokes and high-quality knitting technology, the overall toughness is higher.
The tension of the spokes is 50-110 kgf, and the runout is 0.5-0.6mm.

Packing list

Welcome to send us your enquiry, we will contact you as soon as possible
The message will be saved after closing the window
 
 

FAQ

What is the range of the battery?

The battery is a high quality power lithium-ion battery, 36V, 8.7AH. The range is approximately 90 km+. But that does depend on many various factors, including terrain, slope, your weight and how much you pedal and your level of assist.

What are the battery dimensions?

The battery is 280mm x 75mm.

Can I put the battery in my pannier instead of attaching it to the crossbar?

The battery holder must be positioned at an upward slope, therefore it’s best to be fixed on to your bike-frame. This is because there is a gyroscope inside it, which is part of the pedal assist technology.

What’s included in the kit?

Wheel with 250W/350W motor, battery & battery holder, wired thumb throttle, instruction booklet, charger, tools for installation (allen key and wheel spanner).

Do I have to use the thumb controller?

No. The thumb controller is your choice. We find that some of our customers prefer not to use the thumb controller and that’s fine, the bike will automatically work on the pedal assist mode.

What if I don’t know my wheel/tyre size?

This is a common question.  Your tyre size should be written on the side of your tyre.  There will be a series of numbers showing the diameter and width.  It will look something like this: 700c x 38.  Occasionally different cycle manufacturers will use a different scale.  If you have any problems working out your tyre size, please call us on +86 199 7018 0785.  Alternatively, you can email us a picture of the writing on your tyre to miya@lvbu.tech

Does the kit accommodate hydraulic brakes?

Yes it does. The kit will automatically sense when the brakes are applied and cuts the power to the motor.

Will Lvbu kit fit my bike ?

LVBU kit will fit most bikes except thru axle. 

How does Lvbu kit system work ?
  • Lvbu assist system is an intelligent assist system which can calculate out and provide the proper power based on the speed, acceleration, the slope of the road, and the assist level set in the APP or display. It will provide proper power automatically when you pedal. The motor will not work until the speed reaches 5 km/h. 
  • It will increase the power when it senses the acceleration is positive and decrease the power when it is minus. The system will also increase the power when going uphill and shut down the motor when going downhill. And the kit can also be controlled by the optional wireless thumb throttle. When you push the throttle, the bike will be fully driven by electric power, but when you release it the assist system will kick in again automatically. The introduction of the 5 assist modes is as following:
     * Manual mode: The most often used mode. The users can set a proper assist grade from 0 to 99 for themselves. 0 stands for no assist while 99 stands for the strongest assist. Under the manual mode the user can use the optional wireless display to set the assist grade instead of using smart phone. After setting the assist grade, the wheel will assist automatically.
     * Commute mode: Under this mode, the wheel will have relatively strong assist power all the time. The output curve of the assist grade is as shown above. It is similar to an assist grade of 60% in the manual mode.
     * Leisure mode: The assist power output is as the curve above. It is a curve similar to a damping ratio. Half an hour is a cycle. At the end of the cycle, the assist will become stronger.
     * Exercise mode: This mode has a small assist output. One cycle is also half an hour. After about 10 minutes, the assist power output will become stronger in the rest of the cycle.
     * Climbing mode: The wheel provides a certain assist grade only if the road is uphill that above a certain slope angle. The assist grade and the slope angle can be set in the APP. For example, when you set 2 degrees and an 80 assist grade, the wheel can give you an 80 assist grade when you are on the road with slope angle above 2 degrees.

     Note: Lvbu's intelligent assist system can be upgraded by the APP. We will keep optimizing the algorithm and publishing the new firmware.
How long is the lifetime of the battery?

Lvbu ebike kits use EV 18650 lithium-ion battery cells with class A quality. Working with our own BMS system, the lifetime of the battery is very high. 80% capacity remains after 1,000 cycles. So normally it can last 5 years.

*Note: The definition of one cycle is that charge the battery from 0 to 100% and discharge it fully. For example, if you charge the battery from the 0 to 50% and discharge it to 0, that is 0.5 cycle.

How to connect Lvbu kit with the APP?

Open the APP and allow all the permissions that the APP asks for. And tap the magnified glass icon on the right top of the APP to search for the Bluetooth address. Select the right address of your kit in the list to connect.
 
*Note: Please connect the kit in the APP, don’t connect it in the operation system of the phone. You don’t need to input any pin to connect. And please make sure all permissions are allowed and the kit is not connected to other devices. The kit can just connect to only one device at the same time.

How does Lvbu wheel recognize uphill?

Lvbu wheel has a built-in six-axis gyroscope, which can sense the slope of the road such as uphill and downhill. But if you want to detect the slope of the road correctly, you must calibrate the gyroscope angle on the level ground first. The way how gyroscope works is as below: 

  • The purpose of calibrating the gyroscope angle is to give the gyroscope a horizontal reference, telling the gyroscope that the current angle is level, so that the gyroscope can detect the slope. 
  • If the gyroscope is calibrated on a downhill road, the gyroscope will regard the downhill road with a certain angle as a horizontal road, but when the bike is on a level road, the gyroscope will sense it as an uphill, in that case the motor will always provide assistance; 
  • If the gyroscope is calibrated on an uphill road, the gyroscope will treat this uphill road as a horizontal road. And when the bike is on a level road, the system will shut down the motor because the gyroscope sense the level road as a downhill road by mistake.

    Therefore, you must calibrate the gyroscope on a level ground, otherwise there will be problem with the assist system.
How to connect LVBU ebike kit with Bluetooth display?

BTC02 Display Connect Method:

  • Please turn off or disconnect the Bluetooth connection on your phone before the Bluetooth display connects to the LVBU Wheel. The wheel cannot connect to more than one device at the same time; 
  • Press the power button of the Bluetooth display to turn it on. Then press the power button three times continuously. The display will search for the Bluetooth address of the lvbu ebike kits nearby; 
  • After the display finishes the search, press the up and down keys to select the right address of your kit and press the power button to connect.

DW03 Display Connect Method:

  • Open the APP and connect it with the Lvbu ebike kit
  • Press the power button of the Bluetooth display to turn it on.
  • Tap the "device" icon at the bottom right in the front page of the APP-->Tap "Add Device"--> Select the display in the list to connect.
Do you have a local dealer or oversea warehouse?

Yes, we have oversea warehouse in Europe.

And for some countries, we do have local dealers. 

How long does the battery take to charge?

Approximately 4.5 hours at the mains.  The battery comes with a charger.

Can I buy a spare battery?

Yes. We find the vast majority of people don’t need a spare, but if you want to go on very long bike rides you can double your range by charging a spare battery and taking it with you. You can purchase a spare battery here.

How much does the kit weigh?

The entire kit weights 6.8kg.

Do I need a mobile phone to operate my bike?

No, using your mobile phone is your choice. If you want, you can download the Wepower app, where you can set the pedal assist mode, see the speed, temperature, battery level and mileage covered. But this is entirely optional, and the bike will function perfectly without it.

My bike has disc brakes – will the kit still work?

Yes, the kit fits both V brakes (sometimes called rim brakes) and disc brakes.

How does the pedal assist work?

The kit has an “intelligent assist control module” which works in conjunction with a gyroscope calculating the power you need.  It will assist you automatically when you are pedalling.  The motor will not work until the speed reaches 5km/h. The system will increase the power when you go uphill and will shut down the motor when you are going downhill.  When you brake, the system can detect the decrease of the speed, and will stop the motor.

If you push the thumb throttle the bike will be fully driven by electric power, but when you release it the pedal assist system will kick in again automatically.

Why is there a maximum speed of 15.5mph (25 kph)?

The legal speed limit for e-bikes in some countries is 15.5mph.  Therefore the kit has a default maximum setting of 25kph. It is possible to manually increase the speed up to 35kph (22mph), but this should only be done on private land.

Is the import taxes included in the price? Do I need to pay taxes when I receive the ebike kit?

If the delivery address are in the countries below then you don't need to pay any taxes or VAT:

United Kingdom, United States, Canada, Australia, Russia, France, Germany, Italy, Spain, Sweden, Denmark, Ireland, Belgium, Netherlands, Czech, Republic, Austria, Portugal, Slovakia, Slovenia, Hungary, Bulgaria, Estonia, Greece, Poland, Lithuania, Finland, Latvia, Croatia, Ukraine.

Is Lvbu kit compatible with V brake?

Yes, Lvbu kit is compatible with rim brakes and disc brakes.

And a free new disc can be provided if you need.

Is it safe to use the front wheel drive?

Yes, it’s safe to use the front wheel drive. 

The power of the front wheel motors those lvbu ebike kit use are between 250w to 350w, so there is no safety problem. Actually, there are some advantages to using front motor drive: 

 It is more efficient to pull the bike compared to push the bike.

 The front motor will balance the weight of the front wheel with the rear wheel to make it stabler

 It is much easier to install the front wheel than the back wheel.

What are the functions of the APP?

The APP has two main kinds of functions as following: 

  • Set the parameters:
    ①Search and bind the Lvbu ebike kit: You need to search and bind the kit with the APP when you use it first time.
    ②Calibrate the gyroscope angle: The gyroscope angle must be calibrated after the first time you attach or reattach the kit to your bike.
    ③Set the assist mode or adjust the assist level.
    ④Set over-speed alarm.
    ⑤Set the maximum assist speed (speed limit).
    ⑥Lost report.
    ⑦Firmware upgrade.
    ⑧Restore factory settings.
    ⑨Set the wheel weight, load, wheel size, etc. ...
     After adjusting and setting the parameters, the system will automatically save values instantly.
  • Show cycling data:
    ①Riding speed
    ②Riding mileage: total mileage, current mileage, uphill mileage, etc.
    ③Kit model
    ④Bluetooth address
    ⑤APP version
    ⑥User instructions ...
    We are keeping optimizing the APP all the time, the new version of the firmware and the APP will be released from time to time, you can update it anywhere with the network of your mobile phone.

Do I have to connect to the APP while riding?

No, you don’t have to connect the kit with the APP when you are riding. The assist system is written in the controller, not in the APP. But before the first time you use it, you must calibrate the gyro angle for the bike.
You can set the assist grade in the APP and put your phone in your pocket. The kit will provide proper assist power for you automatically.

What is lvbu kit warranty policy?

For battery, motor and controller, we provide one year warranty.

294 REVIEWS - KF30S Ebike Conversion Kit
Raven Karunanayake
Finland , 6/30/2025
Prompt delivery. Installed in minutes. Worked fine right off the bat. Goes well from a crawl to crazy fast.
Model: KF30S 250W 9Ah Front, 250W Motor, Front wheel ebike kit
Size: 700C (28"), 28 inch rim with tyre
Color: Black, #000000
John Sherry
Finland , 6/28/2025
All I can say is - this wheel has transformed my biking experience! I have a Trek Hybrid 27-speed road bike, probably two years old, which I ride for exercise and fun mostly on local town paved trails. I typically ride 10-15 miles at a time, not wanting to get too tired and have difficulty making it home. Well, with the wheel kit, it's game on! I can ride twice as long/far, having the comfort of knowing that if that hill is a little too steep for me, a flick of the switch will power me up in no time. I love it! And as my wife says....anything that gets me riding more is a good thing. The wheel took me about an hour to install, including strapping the battery into my bike frame properly. I have disc brakes, so that was an additional step that folks who have normal caliper brakes wont face. But it worked from the get-go....no issues at all.
Model: KF30S 250W 9Ah Rear, Ebike kit for rear wheel
Size: 27.5", 27.5 inch rim with tyre
Color: Black, #000000
C. Rayford
Poland , 6/27/2025
I've put 2200 miles on my electric bike kit in 10 months and it has performed marvelously. It's been so much fun hauling my dogs around in their bike trailer with almost no effort unless I choose to. LVBU has performed spectacularly from performance to customer service! I'm happy!
Model: KF30S 350W 9Ah Rear, Ebike kit for rear wheel
Size: 26", 26 inch rim with tyre
Color: Black, #000000
Orcutt Falo
Netherlands , 6/26/2025
I’ve been commuting by bike for over 30 years, and wanted some assistance. I love the new changeand use it for my daily 17 mile commute. It’s been great, with no issues with the battery, motor or wheel.
Model: KF30S 250W 9Ah Front, 250W Motor, Front wheel ebike kit
Size: 26", 26 inch rim with tyre
Color: Blue, #0000ff
Jean Michel Reynaud
Denmark , 6/25/2025
Everything was sent quickly and in good working order. The parts were easy to install and installation was quick. Very happy with the product.
Model: KF30S 250W 9Ah Front, 250W Motor, Front wheel ebike kit
Size: 27.5", 27.5 inch rim with tyre
Color: Black, #000000
Donald Millikin
Germany , 6/24/2025
I am an older man and enjoy little biking adventures; found myself planning shorter trips, concerned about wearing out on the way back. The installation is easily, and seems to be exactly what was required; helps up slopes and on long, boring stretches.
Model: KF30T 250W 9Ah Rear Motor with Torque Sensor, KF30T 250W 9Ah Rear Motor with Torque Sensor
Size: 26", 26 inch rim with tyre
Color: Black, #000000
Barbara Burke
Ireland , 6/23/2025
I have ridden the wheel kit for over 1200 miles this past year. It really works on the many hills on my commute between Seattle and Redmond. The installation was easy and the company quickly answered my questions. Great product and fun to ride!
Model: KF30S 250W 9Ah Front, 250W Motor, Front wheel ebike kit
Size: 700C (28"), 28 inch rim with tyre
Color: Black, #000000
Jennifer Hackwell
Norway , 6/20/2025
This wheel has changed my commute drastically. I am very happy with the range and power. I purchased the 36v system and installed it on my bicycle myself. I hope they will offer a 48v system in the near future
Model: KF30S 350W 9Ah Rear, Ebike kit for rear wheel
Size: 700C (28"), 28 inch rim with tyre
Color: Blue, #0000ff
Steve Frey
Spain , 6/19/2025
Go ahead an buy it already, you wont reget it! i got ir about a yr ago, all i can say is i love it!!! i drive it everywhere, i don't have my license yet so my dad said this is the best thing he could find me to get back an forth from work and going to friends places to hang out. Lets just say i don't know what i would do without it! i like that the set up is simple enough that anyone with a lil knowledge about wires can fix it themselves. over all if your thinking about buying one DON'T HESITATE it will be worth every penny!
Model: KF30S 250W 9Ah Front, 250W Motor, Front wheel ebike kit
Size: 700C (28"), 28 inch rim with tyre
Color: Black, #000000
Ian Craig
Croatia , 6/17/2025
I am very pleased with the product and this company. Would recommend buying from lvbu.
Model: KF30T 250W 9Ah Rear Motor with Torque Sensor, KF30T 250W 9Ah Rear Motor with Torque Sensor
Size: 700C (28"), 28 inch rim with tyre
Color: Black, #000000
Kurt Silva
United Kingdom , 6/16/2025
Have had the unit installed on the bike for approximately 2 weeks but have not been able to ride more then 10 miles due to time restraints. Relatively easy installation with good instructions from them. At this point very pleased with the product. Much better then having to buy a completely new "electric " bike at $2000.00 on up.
Model: KF30T 250W 9Ah Rear Motor with Torque Sensor, KF30T 250W 9Ah Rear Motor with Torque Sensor
Size: 700C (28"), 28 inch rim with tyre
Color: Blue, #0000ff
Roger Flores
Denmark , 6/13/2025
The wheel has been everything we had hoped for! The cost is far less than the many electric bike options out there and has literally made the difference in topping the hill to get to the next town over. Without the motor, the steep hill would be too strenuous an experience to do on a regular basis. Not having to worry about feeding the parking meter is also a huge stress relief.
Model: KF30S 250W 9Ah Front, 250W Motor, Front wheel ebike kit
Size: 700C (28"), 28 inch rim with tyre
Color: Black, #000000
Luis
Netherlands , 6/12/2025
Just received the wheel...so far it is everything I expected...I live in a place that has nothing but hills, and I don't have the training to climb them on my bike. With it, I bike everywhere now. I can climb, and still get a lot of exercise, as the motor helps me but doesn't replace me : ) I will recommend this company, as it has the best price, and is easy to install, and does the trick!!
Model: KF30S 250W 9Ah Front, 250W Motor, Front wheel ebike kit
Size: 700C (28"), 28 inch rim with tyre
Color: Blue, #0000ff
JACQUELINE
Netherlands , 6/11/2025
It's great!!! I have the commuter and I love it!!! all the information that's out there regarding how easy it was to install was correct. I use it to travel my 6 miles to work it's lacks some power on the hills but after all it is power assist. I find myself getting up early on the weekends to get back on it because of the joy of biking. This product and customer service is awesome!!! I.ll be getting another soon for my wife. She is coming off a knee replacer and I believe this will work out fine for her.
Model: KF30S 250W 9Ah Front, 250W Motor, Front wheel ebike kit
Size: 27.5", 27.5 inch rim with tyre
Color: Blue, #0000ff
Vernon Ward
United Kingdom , 6/10/2025
I ordered it over the email, and the unit was installed the same day I received the parcel. It works as advertised and has made riding just that much more enjoyable. Thanks for everything
Model: KF30S 250W 9Ah Front, 250W Motor, Front wheel ebike kit
Size: 27.5", 27.5 inch rim with tyre
Color: Black, #000000
Barry
Malaysia , 6/10/2025
I have not tried the product yet due to surgery, but the ebikekit was easy to install and functions fine. Slight issue with delivery of product but customer service response was positive and issue corrected. Can't wait to test it, more too come....
Model: KF30S 250W 9Ah Front, 250W Motor, Front wheel ebike kit
Size: 26", 26 inch rim with tyre
Color: Blue, #0000ff
Oregon rider
France , 6/9/2025
I ride to work. I have to. This little thing has LITTERALLY saved my life (dodging a car). Its saved me hours of riding, even saving the batteries just for the hills. Its gotten me out of three snowstorms THIS WEEK. Thanks!!!
Model: KF30S 350W 9Ah Front, Ebike kit for front wheel
Size: 700C (28"), 28 inch rim with tyre
Color: Black, #000000
Antonio Torres
Denmark , 6/5/2025
As advertised and all I could do here is repeat what other excellent reviews have said. Good service and nice follow up by Company to be sure all is okay. I am inept at mechanics, however, no problem installing the system. At 72 (and 1/2), while in good shape I sometimes have hesitated going an extra mile or two or venturing off into an unknown area, but, know, if I tire, all I have to do is push a button.. Had ridden a fair distance a week ago and wanted to explore another area, but, a long high bridge was a barrier for my tired legs. No problem. Pushed a button and voila the barrier was conquered and my ride was extended. I do not hesitate to recommend this product.
Model: KF30S 250W 9Ah Front, 250W Motor, Front wheel ebike kit
Size: 27.5", 27.5 inch rim with tyre
Color: Blue, #0000ff
Jochem Brouwers
Spain , 6/4/2025
As someone who’s not very handy, I was a bit nervous, but the install process was incredibly beginner-friendly. Clear instructions, minimal tools needed. Great kit.
Model: KF30T 250W 9Ah Rear Motor with Torque Sensor, KF30T 250W 9Ah Rear Motor with Torque Sensor
Size: 26", 26 inch rim with tyre
Color: Black, #000000
Bernard Bishop
Canada , 6/3/2025
I bought this to convert my hybrid bike, and I’m really impressed. The assist kicks in gently and makes city commuting a breeze. No need to buy a whole new e-bike!
Model: KF30S 250W 9Ah Front, 250W Motor, Front wheel ebike kit
Size: 700C (28"), 28 inch rim with tyre
Color: Black, #000000
Message success
Thanks for your message, Pls. pay attention to your email box. Have a nice day !
Hint