public static void main(String[] args) {
        int grid[][] = {{4, 9, 2}, {3, 5, 7}, {8, 1, 6}};
        System.out.println(isMagicSquare(grid));
    }

    private static boolean isMagicSquare(int[][] grid) {
        int n = grid.length;

        Set<Integer> sums = new HashSet<>();
        int sumOfCurrentRow;
        int sumOfCurrentColumn;

        int sumOfLeftDiagonal = 0;
        int sumOfRightDiagonal = 0;
        for (int i = 0; i < n; i++) {
            sumOfLeftDiagonal += grid[i][i];
            sumOfRightDiagonal += grid[n - 1 - i][i];

            sumOfCurrentRow = 0;
            sumOfCurrentColumn = 0;
            for (int j = 0; j < n; j++) {
                sumOfCurrentRow += grid[i][j];
                sumOfCurrentColumn += grid[j][i];
            }

            if (sums.isEmpty()) {
                sums.add(sumOfCurrentRow);
            } else {
                if (sums.add(sumOfCurrentRow)) {
                    return false;
                }
            }

            if (sums.add(sumOfCurrentColumn)) {
                return false;
            }
        }

        return !sums.add(sumOfLeftDiagonal) && !sums.add(sumOfRightDiagonal);
    }