Problem 45418. En passant - 01

This is white's turn. The player moves his pawn.

The pawn's previous and current positions are given.

Determine whether the move was valid.

 pawn's previous pos = 'b2'
 pawn's previous pos = 'c3'

So this is a valid move provided there was an opponent piece on c3.

But for now, just check the validity of the move. Opponent's pieces will be added in the next problem.

https://en.wikipedia.org/wiki/Chess#Movement