#include "soccer.h"

#include <cassert>
#include <cmath>
#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <functional>
#include <iostream>
#include <limits>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

using namespace std;

using Int = long long;

template <class T1, class T2> ostream &operator<<(ostream &os, const pair<T1, T2> &a) { return os << "(" << a.first << ", " << a.second << ")"; };
template <class T> ostream &operator<<(ostream &os, const vector<T> &as) { const int sz = as.size(); os << "["; for (int i = 0; i < sz; ++i) { if (i >= 256) { os << ", ..."; break; } if (i > 0) { os << ", "; } os << as[i]; } return os << "]"; }
template <class T> void pv(T a, T b) { for (T i = a; i != b; ++i) cerr << *i << " "; cerr << endl; }
template <class T> bool chmin(T &t, const T &f) { if (t > f) { t = f; return true; } return false; }
template <class T> bool chmax(T &t, const T &f) { if (t < f) { t = f; return true; } return false; }


int N;
bool A[2010][2010];

int whole() {
  int x0 = N, x1 = -1;
  vector<int> ls(N, N), rs(N, -1);
  for (int x = 0; x < N; ++x) for (int y = 0; y < N; ++y) if (A[x][y]) {
    chmin(x0, x);
    chmax(x1, x);
    chmin(ls[x], y);
    chmax(rs[x], y);
  }
  assert(x0 <= x1);
  for (int x = x0; x <= x1; ++x) {
    for (int y = ls[x]; y <= rs[x]; ++y) {
      if (!A[x][y]) return 0;
    }
  }
  int x2 = x0;
  for (int x = x0; x <= x1; ++x) {
    if (rs[x2] - ls[x2] < rs[x] - ls[x]) {
      x2 = x;
    }
  }
  for (int x = x0; x < x2; ++x) {
    if (!(ls[x] >= ls[x + 1])) return 0;
    if (!(rs[x] <= rs[x + 1])) return 0;
  }
  for (int x = x1; x > x2; --x) {
    if (!(ls[x] >= ls[x - 1])) return 0;
    if (!(rs[x] <= rs[x - 1])) return 0;
  }
  
  int area = 0;
  for (int x = 0; x < N; ++x) for (int y = 0; y < N; ++y) if (A[x][y]) {
    ++area;
  }
  return area;
}

int biggest_stadium(int N_, std::vector<std::vector<int>> F)
{
  N = N_;
  for (int x = 0; x < N; ++x) for (int y = 0; y < N; ++y) {
    A[x][y] = !F[x][y];
  }
  return whole();
}