text: // Given a 2D array of integers, find the maximum sum 2D subarray
  // Performing the 1D maxsum algorithm on the columns of all O(n^2) consecutive set of rows
  // Time complexity: O(n^3)
  // Problem link: https://vjudge.net/problem/UVA-108
  
  #include <bits/stdc++.h>
  
  using namespace std;
  
  #define ar array
  #define ll long long
  
  const int MAX_N = 1e5 + 1;
  const int MOD = 1e9 + 7;
  const int INF = 1e9;
  const ll LINF = 1e18;
  
  
  
  void solve() {
      int n; cin >> n;
      ll ps[n + 1][n + 1] = {};
      // Creating a prefix sum table (horizontally)
      for (int i = 1; i <= n; i++) {
          for (int j = 1; j <= n; j++) {
              cin >> ps[i][j];
              ps[i][j] += ps[i][j - 1];
          }
      }
  
      // 2D max sum subarray
      ll ans = 0;
      for (int l = 1; l <= n; l++) { // looping through all pairs of columns, running 1D maxsum on a column
          for (int r = l; r <= n; r++) {
              ll cur = 0;
              for (int i = 1; i <= n; i++) {
                  ll x = ps[i][r] - ps[i][l - 1];
                  cur = max(0ll, cur + x);
                  ans = max(ans, cur);        
              }
          }
      }
      cout << ans << "\n";
  }
  
  int main() {
      ios_base::sync_with_stdio(0);
      cin.tie(0); cout.tie(0);
      // freopen("input.txt", "r", stdin);
      // freopen("output.txt", "w", stdout);
  
      int tc; tc = 1;
      for (int t = 1; t <= tc; t++) {
          // cout << "Case #" << t  << ": ";
          solve();
      }
  }