/// <summary>
/// Gets a square position from its rank and file chars.
/// </summary>
/// <param name="f">The file char</param>
/// <param name="r">The rank char</param>
/// <returns></returns>
public static int GetPosition(char f, char r)
{
if (f < 'a' || f > 'h' || r < '1' || r > '8')
{
return(-1);
}
return(Board.Position('8' - r, f - 'a'));
}