static boolean isBlackPiece(int i, int j) {
        if ((i < 0) || (j < 0)) {
            return true;
        }
        if ((i > 11) || (j > 11)) {
            return true;
        }
        return (board[i][j] == 'p')
                || (board[i][j] == 't')
                || (board[i][j] == 'n')
                || (board[i][j] == 'c')
                || (board[i][j] == 'd')
                || (board[i][j] == 'r');
    }