class Solution {
    public List<Integer> luckyNumbers(int[][] matrix) {
        int N = matrix.length, M = matrix[0].length;

        int rMinMax = Integer.MIN_VALUE;
        for (int i = 0; i < N; i++) {
            int rMin = Integer.MAX_VALUE;
            for (int j = 0; j < M; j++) {
                rMin = Math.min(rMin, matrix[i][j]);
            }
            rMinMax = Math.max(rMinMax, rMin);
        }

        int cMaxMin = Integer.MAX_VALUE;
        for (int i = 0; i < M; i++) {
            int cMax = Integer.MIN_VALUE;
            for (int j = 0; j < N; j++) {
                cMax = Math.max(cMax, matrix[j][i]);
            }
            cMaxMin = Math.min(cMaxMin, cMax);
        }

        if (rMinMax == cMaxMin) {
            return List.of(rMinMax);
        }

        return new ArrayList<>();
    }
}