#include <bits/stdc++.h>

using namespace std;

using ll = long long;
const int MOD = 1E9 + 7;
const int INF = 1E9; const ll INFLL = 1E18;

const int MAX = 2001;
const int LOG = 11;
int lg[MAX];

struct SparseTable {
	int n;
	vector<vector<int>> sparse;
	SparseTable(int n) {
		this->n = n;
		sparse.assign(n, vector<int>(LOG));
	}
	void build(vector<int>& a) {
		for(int i = 0; i < n; i++) {
			sparse[i][0] = a[i];
		}
		for(int i = 1; i < LOG; i++) {
			for(int j = 0; j + (1 << i) - 1 < n; j++) {
				sparse[j][i] = max(sparse[j][i - 1], sparse[j + (1 << (i - 1))][i - 1]);
			}
		}
	}
	int query(int l, int r) {
		int k = lg[r - l + 1];
		return max(sparse[l][k], sparse[r - (1 << k) + 1][k]);
	}
};

int biggest_stadium(int N, vector<vector<int>> F) {
	lg[1] = 0;
	for(int i = 2; i < MAX; i++) {
		lg[i] = lg[i / 2] + 1;
	}
	vector<vector<int>> treeUp(N, vector<int>(N, -1));
	vector<vector<int>> treeDown(N, vector<int>(N, N));
	vector<SparseTable> sUp(N, SparseTable(N));
	vector<SparseTable> sDown(N, SparseTable(N));
	vector<set<int>> treeRows(N);
	for(int i = 0; i < N; i++) {
		for(int j = 0; j < N; j++) {
			if(i) {
				treeUp[i][j] = treeUp[i - 1][j];
			}
			if(F[i][j]) {
				treeUp[i][j] = i;
				treeRows[i].insert(j);
			}
		}
	}
	for(int i = N - 1; i >= 0; i--) {
		for(int j = 0; j < N; j++) {
			if(i + 1 < N) {
				treeDown[i][j] = treeDown[i + 1][j];
			}
			if(F[i][j]) {
				treeDown[i][j] = i;
			}
		}
	}
	for(int i = 0; i < N; i++) {
		for(int j = 0; j < N; j++) {
			treeDown[i][j] *= -1;
		}
		sUp[i].build(treeUp[i]);
		sDown[i].build(treeDown[i]);
	} 
	vector<map<array<int, 4>, int>> width(N);
	array<int, 4> v = {0, 0, 0, 0};
	for(int i = 0; i < N; i++) {
		for(int j = 0; j < N; j++) {
			int k = j;
			while(k < N && !F[i][k]) {
				k++;
			}
			if(!F[i][j]) {
				int wid = k - j - 1;
				int x1; int y1; int x2; int y2;
				y1 = j; y2 = k - 1;
				x1 = sUp[i].query(y1, y2) + 1;
				x2 = -sDown[i].query(y1, y2) - 1;
				width[wid][{x1, y1, x2, y2}] = (y2 - y1 + 1) * (x2 - x1 + 1);
			}
			j = k; 
		}
	}
	int ans = 0;
	for(int i = N - 1; i >= 0; i--) {
		for(pair<array<int, 4>, int> j : width[i]) {
			ans = max(ans, j.second);
			int x1 = j.first[0]; int y1 = j.first[1]; int x2 = j.first[2]; int y2 = j.first[3];
			if(x1) {
				vector<int> pts(1, y1 - 1);
				set<int>::iterator it = treeRows[x1 - 1].lower_bound(y1);
				while(it != treeRows[x1 - 1].end() && *it <= y2) {
					pts.push_back(*it);
					++it;
				}
				pts.push_back(y2 + 1);
				for(int k = 0; k + 1 < pts.size(); k++) {
					if(pts[k + 1] > pts[k] + 1) {
						int nx1; int ny1; int nx2; int ny2;
						ny1 = pts[k] + 1; ny2 = pts[k + 1] - 1;
						nx1 = sUp[x1 - 1].query(ny1, ny2) + 1;
						if(x2 + 1 < N) {
							nx2 = -sDown[x2 + 1].query(ny1, ny2) - 1;
						} else {
							nx2 = x2;
						}
						int wid = ny2 - ny1;
						int addArea = (ny2 - ny1 + 1) * (nx2 - nx1 + 1) - (ny2 - ny1 + 1) * (x2 - x1 + 1);
						width[wid][{nx1, ny1, nx2, ny2}] = max(width[wid][{nx1, ny1, nx2, ny2}], j.second + addArea);
					}  
				}
			}
			if(x2 + 1 < N) {
				vector<int> pts(1, y1 - 1);
				set<int>::iterator it = treeRows[x2 + 1].lower_bound(y1);
				while(it != treeRows[x2 + 1].end() && *it <= y2) {
					pts.push_back(*it);
					++it;
				}
				pts.push_back(y2 + 1);
				for(int k = 0; k + 1 < pts.size(); k++) {
					if(pts[k + 1] > pts[k] + 1) {
						int nx1; int ny1; int nx2; int ny2;
						ny1 = pts[k] + 1; ny2 = pts[k + 1] - 1;
						if(x1) {
							nx1 = sUp[x1 - 1].query(ny1, ny2) + 1;
						} else {
							nx1 = x1;
						}
						nx2 = -sDown[x2 + 1].query(ny1, ny2) - 1;
						int wid = ny2 - ny1;
						int addArea = (ny2 - ny1 + 1) * (nx2 - nx1 + 1) - (ny2 - ny1 + 1) * (x2 - x1 + 1);
						width[wid][{nx1, ny1, nx2, ny2}] = max(width[wid][{nx1, ny1, nx2, ny2}], j.second + addArea);
					}
				}
			}
		}
	} 
	return ans;
}