SUM.cpp

#include <bits/stdc++.h>
using namespace std;

// ----------- define --------------
#define int long long
#define vi vector<int>
#define ii pair<int,int>
#define fi first
#define sc second
#define mp make_pair
#define pqueue priority_queue
#define popcnt __builtin_popcount
#define getBit(x, k) ((x >> k) & 1)
#define xorBit(x, k) (x ^ (1 << k))
#define siz(x) (int)((x).size())
#define all(x) (x).begin(),(x).end()
// ---------------------------------

void Main() {
  int n; cin >> n;
  vector<vi> a(n + 1, vi(n + 1));
  int ans = 0;
  for (int i = 1; i <= n; i++)
  for (int j = 1; j <= n; j++) {
    cin >> a[i][j];
    a[i][j] += a[i - 1][j - 1];
    if (i == n || j == n) {
      ans = max(ans, a[i][j]);
    }
  }
  cout << ans << '\n';
}

signed main() {
  freopen("SUM.inp", "r", stdin );
  freopen("SUM.out", "w", stdout);
  cin.tie(0)->sync_with_stdio(0);
  int T = 1;
  // cin >> T;
  while (T--) Main();
}