private int checkCross(GameBoardMark playerMark) {
        int k, l, x;

        for (k = 1; k < 7; k++) {
            for (l = 1; l < 7; l++) {
                x = k + 10 * l;
                if (gameBoard.mainBoard()[x] == playerMark.index && gameBoard.mainBoard()[x + 2] == playerMark.index && gameBoard.mainBoard()[x + 20] == playerMark.index && gameBoard.mainBoard()[x + 22] == playerMark.index && gameBoard.mainBoard()[x + 11] == 0) return (x + 11);
            }
        }
        return GameBoard.oneMoreThanLastPositionOnBoard;
    }