#define _CRT_SECURE_NO_DEPRECATE
#include<iostream>
#include<algorithm>
#include<string>
#include<set>
#include<map>
#include<vector>
#include<queue>
#include<functional>
using namespace std;
const int N_MAX= 100+2;
int a[N_MAX][N_MAX];
int sum[N_MAX][N_MAX];
int main() {
    int n;
    while (scanf("%d", &n) != EOF) {
        memset(sum,0,sizeof(sum));
        memset(a, 0,sizeof(a));
        for (int i = 0; i < n; i++) {
            for (int j = 1; j <= n; j++) {
                scanf("%d", &a[i][j]);
            }
        }
        for (int i = 0; i < n; i++) {
            for (int j = 1; j <= n; j++) {
                 sum[i][j] =sum[i][j-1]+ a[i][j];
            }
        }
        
        int res = -INT_MAX;
        for (int i = 0; i < n; i++) {//固定i,j
            for (int j = i+1; j <= n; j++) {
                int S = 0;
                for (int k = 0; k < n; k++) {
                    S += sum[k][j]-sum[k][i-1];//累加上闭区间[i,j]值的和
                    if (S > res)
                        res = S;
                    if (S < 0)S = 0;
                    
                }
            }
        }
        printf("%d\n",res);

    }
return 0;
}