#include <bits/stdc++.h>
using namespace std;
const int N = 130;
int n;
int a[N][N];  // 存储题目中的矩阵
int s[N][N];  // 二维前缀和
int qz[N][N]; // qz[i][j]指的是第i行到j的前缀和

int main() {
    cin >> n;
    for (int i = 1; i <= n; i++) {
        for (int j = 1; j <= n; j++) {
            cin >> a[i][j];
            qz[i][j] = qz[i][j - 1] + a[i][j]; // 求前缀和
            s[i][j] = qz[i][j] + s[i - 1][j];  // 计算s
        }
    }

    int mx = INT_MIN; // 存储答案
    // 遍历左上角坐标，与，右下角坐标
    for (int x1 = 1; x1 <= n; x1++) {
        for (int y1 = 1; y1 <= n; y1++) {
            for (int x2 = 1; x2 <= n; x2++)
                for (int y2 = 1; y2 <= n; y2++) {
                    if (x2 < x1 || y2 < y1) continue;                                            // 如果左上角比右下角还要大，就不用求了，下一个
                    mx = max(mx, s[x2][y2] + s[x1 - 1][y1 - 1] - s[x2][y1 - 1] - s[x1 - 1][y2]); // 求最大值
                }
        }
    }
    cout << mx << endl; // 输出
    return 0;
}