/*Maximum Subarray*/

/*
normal : O(N^4)
best : O(N^3)
*/







#include<iostream>
#include<cstring>
#include<algorithm>
#define maxn 100+5
using namespace std;
int n, matrix[maxn][maxn], cur_matrix[maxn];

int find_max() {

 //calculate maximum subarray each row
 int cur_sum = 0, sum = 0;
 for (int l = 0; l < n; l++) {
  sum += cur_matrix[l];
  cur_sum = max(sum, cur_sum);
  if (sum < 0) sum = 0;
 }
 return cur_sum;
}

void ans() {

 //compress
 int MaxSum = -200;
 for (int i = 0; i < n; i++) {
  memset(cur_matrix, 0, sizeof(cur_matrix));
  for (int j = i; j < n; j++) {
   for (int k = 0; k < n; k++) {
    cur_matrix[k] += matrix[j][k];
   }
   MaxSum = max(MaxSum, find_max());
  }
 }
 cout << MaxSum << endl;
}

int main(void) {

 while (cin >> n) {
  for (int i = 0; i < n; i++) {
   for (int j = 0; j < n; j++) {
    cin >> matrix[i][j];
   }
  }
  ans();
 }

 return 0;
}