#include <bits/stdc++.h>
using namespace std;
int a[105][105],b[105][105],f[105][105],mx = -1e7;
int main(int argc, char **argv){
	// 前缀和：b[x][y] = a[x][y] + b[x - 1][y] + b[x][y - 1] - b[x - 1][y - 1];
	// 区间和：a[x2][y2] = b[x2][y2] - b[x2][y1 - 1] - b[x1 - 1][y2] + b[x1 - 1][y1 - 1];
	int n;
	cin >> n;
	for (int x = 1;x <= n;x++){
		for (int y = 1;y <= n;y++){
			cin >> a[x][y];
			b[x][y] = a[x][y] + b[x - 1][y] + b[x][y - 1] - b[x - 1][y - 1];	// 前缀和
		}
	}

	for (int x2 = 1;x2 <= n;x2++){
		for (int y2 = 1;y2 <= n;y2++){
			for (int x1 = 1;x1 <= n;x1++){
				for (int y1 = 1;y1 <= n;y1++){
					f[x2][y2] = max(f[x2][y2],b[x2][y2] - b[x2][y1 - 1] - b[x1 - 1][y2] + b[x1 - 1][y1 - 1]);	// 找最大的区间
				}
			}
			mx = max(mx,f[x2][y2]);
		}
	}
	cout << mx;
	return 0;
}