115.cpp

#include <stdio.h>
#include <vector>
#include <algorithm>

int main() {
    freopen("input.txt", "rt", stdin);
    freopen("output.txt", "wt", stdout);

    int rows, cols;
    scanf("%d %d", &rows, &cols);

    int max = -100;

    std::vector<std::vector<int>> sum(1+rows, std::vector<int>(1+cols, 0));
    for (int r = 1; r <= rows; ++r)
        for (int c = 1; c <= cols; ++c) {
            int v;
            scanf("%d", &v);
            sum[r][c] = sum[r-1][c] + v;
            max = std::max(max, v);
        }

    if (max > 0) {
        for (int r1 = 1; r1 <= rows; ++r1)
            for (int r2 = r1; r2 <= rows; ++r2) {
                int s = 0;
                for (int c = 1; c <= cols; ++c) {
                    s += sum[r2][c] - sum[r1-1][c];
                    if (s < 0) s = 0;
                    max = std::max(max, s);
                }
            }
    }

    printf("%d", max);

    return 0;
}