Grapevine TLE

#include <stdio.h>
#include <algorithm>
using namespace std;

int n,m;
int map[510][510];
int q,l,u;

int square(int i, int j) {
    if (map[i][j]<l || map[i][j]>u)
        return 0;

    int beg=0, end=min(n-i,m-j)-1;

    while (beg<end) {
        int mid=(beg+end+1)/2;

        if (map[i+mid][j+mid]<=u) beg=mid;
        else end=mid-1;
    }

    return beg+1;
}

int main() {
    while (1) {
        scanf("%d %d", &n,&m);
        if (!n && !m)
            break;

        for (int i=0; i<n; i++)
            for (int j=0; j<m; j++)
                scanf("%d", &map[i][j]);

        scanf("%d", &q);

        while (q--) {
            scanf("%d %d", &l,&u);
            int big=0;

            for (int i=0; i<n; i++)
                for (int j=0; j<m; j++)
                    big=max(big,square(i,j));
            printf("%d\n", big);
        }
        printf("-\n");
    }

    return 0;
}