#include<iostream>
#include<stdio.h>
using namespace std;
int n, a[401][401], s[401][401], ans = 0;
bool ok = false;
void in()
{ scanf("%d", &n);
  for (int i = 0; i < n; i++)
  { scanf("%d", &a[i][0]);
    s[i][0] = a[i][0];
    
    if (a[i][0] > 0)
      ok = true;
    
    for (int j = 1; j < n; j++)
    { scanf("%d", &a[i][j]);
      
      if (a[i][j] > 0)
        ok = true;
      
      s[i][j] = s[i][j - 1] + a[i][j];
    }
  }
}

void solve()
{ if (ok == false)
  { ans = a[0][0];
    for (int i = 0; i < n; i++)
      for (int j = 0; j < n; j++)
        if (a[i][j] > ans)
          ans = a[i][j];
    
    printf("%d\n", ans);
    return;
  }
  
  for (int i = 0; i < n; i++)
    for (int j = i; j < n; j++)
    { int sum = 0;
      for (int k = 0; k < n; k++)
      { int element = s[k][j] - s[k][i] + a[k][i];
        sum += element;
        
        if (sum < 0)
          sum = 0;
        
        if (sum > ans)
          ans = sum;
      }
    }
  
  printf("%d\n", ans);
}

int main()
{ 
  in();
  solve();
  
  return 0;
}