// Online C++ compiler to run C++ program online
#include <iostream>
#include <bits/stdc++.h>
#define ll long long
#define endll '\n'
#define FOR for(int i = 1; i <= n; i++)
using namespace std;
void fastIO()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
cout.tie(NULL);
}
ll a[1001][1001];
int main() {
fastIO();
int n , m; cin >> n >> m;
for(int i = 1; i <= n; ++i)
{
for(int j = 1; j <= m ; ++j)
{
cin >> a[i][j];
}
}
for(int i = 1; i <= n; ++i)
{
for(int j = 1; j <= m ; ++j)
a[i][j] += a[i][j - 1];
}
for(int i = 1; i <= m; ++i)
{
for(int j = 1; j <= n ; ++j)
a[j][i] += a[j - 1][i];
}
int x,y; cin >> x >> y;
ll mx = LLONG_MIN;
for (int down = x; down <= n; ++down )
{
for(int right = y; right <= m; ++right)
{
int left = right - y + 1;
int up = down - x + 1;
mx = max(mx, a[down][right] - a[up-1][right] - a[down][left-1] + a[up - 1][left - 1]);
}
}
cout << mx << endll;
return 0;
}
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