P2346 Connect Four

The input testdata for this problem contains `\r\n`; please use `cin` or `scanf` for input.

On a $4\times 4$ board there are $14$ pieces: $7$ white and $7$ black, with two empty cells. Any piece may move up, down, left, or right into an adjacent empty cell; this counts as one move. Black and white move alternately, and either side may move first. If at any time the pieces of either color form four in a line (including diagonals), that state is a target board position. 

Read a $4\times 4$ initial board from the file. Black pieces are denoted by `B`, white pieces by `W`, and empty cells by `O`.

Output the minimum number of moves required to reach a target board position.

Translated by ChatGPT 5