#define  _CRT_SECURE_NO_WARNINGS
#include <iostream>
using namespace std;
#include <vector>
#include <set>
#include <map>
#include <unordered_map>
#include <cstdio>
#include <cstring>
#include <queue>
#include <cstdlib>
#include <algorithm>
#include <list>
#include <string>
#include <cmath>
#include <bitset>

using namespace std;
using ll = long long;
#define LF(x) fixed << setprecision(x)
typedef pair<int, int> pii;
#define endl "\n"


int nums[125][125];
int main() {

	int n; cin >> n;
	for (int i = 1; i <= n; i++) 
		for (int j = 1; j <= n; j++) 
			cin >> nums[i][j];
	int m = -9999;
	for (int i = 1; i <= n; i++) {

		vector<int>num(n + 1);
      //压缩矩阵
		for (int j = 1; j <= n; j++)
			for (int k = 1; k <= i; k++)
				num[j] += nums[j][k];
		//求字段和
		for (int k = 1; k <= n; k++) {
			num[k] = max(num[k - 1] + num[k], num[k]);
			m = max(m, num[k]);
		}
	}


	cout << m << endl;

	return 0;
}