#include<bits/stdc++.h>
using namespace std;
const int maxn = 130;
int n, a[maxn][maxn], sum[maxn][maxn];
int main () {
	cin >> n;
	for (int i = 1; i <= n; i++ ) {
		for (int j = 1; j <= n; j++ ) {
			cin >> a[i][j];
		}
	}
	for (int i = 1; i <= n; i++ ) {
		for (int j = 1; j <= n; j++ ) {
			sum[i][j] = sum[i - 1][j] + sum[i][j - 1] - sum[i - 1][j - 1] + a[i][j];
		}
	}
	int ans = -0x3f3f3f3f;
	for (int len = 1; len <= n; len++ ) {
		for (int i = 1; i + len - 1<= n; i++ ) {
			for (int j = 1; j + len - 1<= n; j++ ) {
				int ii = i + len - 1;
				int jj = j + len - 1;
				int tmp = sum[ii][jj] - sum[i - 1][jj] - sum[ii][j - 1] + sum[i - 1][j - 1];				
				ans = max (ans, tmp);
			}
		}
	}
	cout << ans;
}