Write a unit conversion program that asks the users from which unit they want to convert $($ft or mi$)$ and to which unit they want to convert $($cm$,$ m$,$ km$).$ Reject incompatible conversions $($such as gal $->$ km$).$ Ask for the value to be converted, then display the result:

Convert from? ft

Convert to$?$ km

Value? $6250$

$6250$ ft $=1\mathrm{.}905$ k