Grapevine errado

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

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

inline int fits(int i, int j, int k) {
    return map[i+k][j+k]>=l &&
            map[i+k][j+k]<=u;
}

inline bool inMap(int i, int j) {
    return i>=0 && i<n && j>=0 && j<m;
}

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

    while (!inMap(i+end-1,j+end-1))
        end++;
    while (inMap(i+end+1,j+end+1))
        end++;

    tmpEnd=end;

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

        if (fits(i,j,mid)) end=mid;
        else beg=mid+1;
    }

    if (!fits(i,j,beg))
        return 0;

    low=beg;
    beg=0, end=tmpEnd;

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

        if (fits(i,j,mid)) beg=mid;
        else end=mid-1;
    }

    return beg-low+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++)
                big=max(big,biggest(i,0));

            for (int i=0; i<m; i++)
                big=max(big,biggest(0,i));

            printf("%d\n", big);
        }
        printf("-\n");
    }

    return 0;
}