MUST be able to submit within next 12 hours.
1. define a function named main()
2. get input to a main function and pass it to the following functions:
milesToKm() , FahToCel() , GalToLit() , PoundsToKg() , InchesToCm()
3. each function must have a local variable to store the result of the calculation. this result will be displayed using the print statement from within the function