#include<stdio.h>

int n,i,j,lin,sc,sm,v[101],a[101][101],sol;

int main()
{

   scanf("%d",&n);

   for(i = 1; i <= n; i++)
    for(j = 1; j <= n; j++)
     scanf("%d",&a[i][j]);

   for(i = 2;i <= n; i++)
    for(j = 1;j <= n; j++)
     a[i][j] += a[i-1][j];

   sol = -1000001;
   for(lin = 1;lin <= n; lin++)
     for(i = lin;i <= n;i++)
      {
          for(j = 1; j <= n; j++)
             v[j] = a[i][j] - a[i-lin][j];

          sc = 0; sm =- 1000001;
         for(j = 1;j <= n;j++)
         {
             sc += v[j];
            sm = (sc > sm) ? sc : sm;
            sc = (sc > 0) ? sc : 0;
         }
         sol = (sm > sol) ? sm : sol;
     }

    printf("%d\n",sol);
   return 0;
}