1 //2016.8.21
 2 #include<iostream>
 3 #include<cstdio>
 4 #include<cstring>
 5 
 6 using namespace std;
 7 
 8 const int N = 105;
 9 const int inf = 0x3f3f3f3f;
10 int a[N][N];
11 
12 int main()
13 {
14     int n, tmp;
15     while(scanf("%d", &n)!=EOF)
16     {
17         for(int i = 0; i < n; i++)
18               for(int j = 0; j < n; j++)
19                   scanf("%d", &a[i][j]);
20         
21         int ans = -inf;
22         for(int i = 0; i < n-1; i++)
23         {
24 //把第j行合并到第i行，求出第i行到第j行的最大子段和**************
25             for(int j = i; j < n; j++)
26             {
27                 tmp = 0;
28                 for(int k = 0; k < n; k++)
29                 {
30                     if(j > i) a[i][k]+=a[j][k];//把矩阵合并为一维的数组
31                     if(tmp > 0) tmp += a[i][k];
32                     else tmp = a[i][k];
33                     ans = max(ans, tmp);
34                 }
35             }
36 //**************************************************************            
37         }
38 
39         cout<<ans<<endl;
40     }
41 
42     return 0;
43 }