#include <iostream>
using
namespace
std;
const
int
SIZE = 100;
int
matrix[SIZE + 1][SIZE + 1];
int
rowsum[SIZE + 1][SIZE + 1];
int
m, n, i, j, first, last, area, ans;
int
main()
{
cin >> m >> n;
for
(i = 1; i <= m; i++)
for
(j = 1; j <= n; j++)
cin >> matrix[i][j];
ans = matrix ①;
for
(i = 1; i <= m; i++)
②
for
(i = 1; i <= m; i++)
for
(j = 1; j <= n; j++)
rowsum[i][j] = ③;
for
(first = 1; first <= n; first++)
for
(last = first; last <= n; last++)
{
④;
for
(i = 1; i <= m; i++)
{
area += ⑤;
if
(area > ans)
ans = area;
if
(area < 0)
area = 0;
}
}
cout << ans << endl;
return
0;