// #include "closing.h"
#include <bits/stdc++.h>
using namespace std;
// #pragma GCC optimize ("Ofast")
// #pragma GCC target ("avx2")
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<long long, long long> pll;
#define el << '\n'
#define nl cout << '\n'
#define spc << ' '
#define forn(i,n) for (int i=0; i<n; i++)
#define forl(i,s,e) for (int i=s; i<e; i++)
#define pb push_back
#define fi first
#define se second
#define rsz resize
#define sz(x) ((int) x.size())
#define all(x) x.begin(), x.end()
const int inf = 1000000000;
const ll inf2 = 4000000000000000000;

// 0 -> (1, 0), down
// 1 -> (0, 1), right
// 2 -> (-1, 0), up
// 3 -> (0, -1), left

const int MAXN = 2005;
int n;
bool f[MAXN][MAXN];
int nt[MAXN][MAXN][4];

int lg(int k) {
	return 32-__builtin_clz(k);
}

void smax(int& a, int b) {
	if (b>a) a=b;
}

void gnt() {
	forn(i,n) {
		int lp[4] = {n, n, -1, -1};
		forn(j,n) {
			if (f[i][j]) lp[3] = j;
			if (f[j][i]) lp[2] = j;
			nt[i][j][3] = lp[3];
			nt[j][i][2] = lp[2];
		}
		for (int j = n-1; j>=0; j--) {
			if (f[i][j]) lp[1] = j;
			if (f[j][i]) lp[0] = j;
			nt[i][j][1] = lp[1];
			nt[j][i][0] = lp[0];
		}
	}
}

vector<pii> st[MAXN][MAXN][4];

void gst() {
	forn(i,n) {
		for (int j = n-1; j>=0; j--) {
			int l = lg(n-j);
			st[i][j][0].rsz(l);
			st[j][i][1].rsz(l);
			st[i][j][2].rsz(l);
			st[j][i][3].rsz(l);
			st[i][j][0][0] = {nt[i][j][0], j};
			st[j][i][1][0] = {nt[j][i][1], j};
			st[i][j][2][0] = {nt[i][j][2], j};
			st[j][i][3][0] = {nt[j][i][3], j};
			forl(js, 1, l) {
				int dt = j + (1<<(js-1));
				st[i][j][0][js] = min(st[i][j][0][js-1], st[i][dt][0][js-1]);
				st[j][i][1][js] = min(st[j][i][1][js-1], st[dt][i][1][js-1]);
				st[i][j][2][js] = max(st[i][j][2][js-1], st[i][dt][2][js-1]);
				st[j][i][3][js] = max(st[j][i][3][js-1], st[dt][i][3][js-1]);
			}
		}
	}
}

pii rq(int x, int y1, int y2, int qt) {
	int l = lg(y2-y1)-1;
	int y3 = y2 - (1<<l) + 1;
	if (qt==0) return min(st[x][y1][0][l], st[x][y3][0][l]);
	if (qt==1) return min(st[y1][x][1][l], st[y3][x][1][l]);
	if (qt==2) return max(st[x][y1][2][l], st[x][y3][2][l]);
	return max(st[y1][x][3][l], st[y3][x][3][l]);
}

int dp[MAXN][MAXN];
int rb[MAXN][MAXN][4];

void gr() {
	forn(i,n) {
		forn(j,n) {
			if (f[i][j]) {
				rb[i][j][0] = -1;
				continue;
			}
			rb[i][j][3] = j;
			int k = nt[i][j][1] - 1;
			rb[i][j][1] = k;
			rb[i][j][0] = rq(i, j, k, 0).fi-1;
			rb[i][j][2] = rq(i, j, k, 2).fi+1;
		}
	}
}

struct rt{
	int x, y, w;
};

bool operator < (const rt& r1, const rt& r2) {
	return r1.w < r2.w;
}

int solve() {
	vector<rt> oo;
	forn(i,n) forn(j,n) if (rb[i][j][0] != -1) oo.pb({i, j, rb[i][j][1] - rb[i][j][3] + 1});
	sort(all(oo));
	int ans = 0;
	for (rt i : oo) {
		if (dp[i.x][i.y] == 0) dp[i.x][i.y] = (rb[i.x][i.y][0] - rb[i.x][i.y][2] + 1) * i.w;
		pii temp = rq(i.x, i.y, rb[i.x][i.y][1], 2);
		int v1 = (temp.fi>=0 && !f[temp.fi][i.y]? temp.se : inf);
		temp = rq(i.x, i.y, rb[i.x][i.y][1], 0);
		int v2 = (temp.fi<n && !f[temp.fi][i.y] ? temp.se : inf);
		if (v1 != inf) {
			int v = rb[i.x][i.y][2]-1;
			smax(dp[i.x][i.y], dp[v][i.y] + (rb[i.x][i.y][1] - rb[v][i.y][1]) * (rb[i.x][i.y][0] - rb[i.x][i.y][2] + 1));
		}
		if (v2 != inf) {
			int v = rb[i.x][i.y][0]+1;
			smax(dp[i.x][i.y], dp[v][i.y] + (rb[i.x][i.y][1] - rb[v][i.y][1]) * (rb[i.x][i.y][0] - rb[i.x][i.y][2] + 1));
		}
		smax(ans, dp[i.x][i.y]);
		if (i.y && !f[i.x][i.y-1]) smax(dp[i.x][i.y-1], dp[i.x][i.y] + rb[i.x][i.y-1][0] - rb[i.x][i.y-1][2] + 1);
	}
	return ans;
}

int biggest_stadium(int N, vector<vector<int>> F) {
	n = N;
	forn(i,n) forn(j,n) f[i][j] = F[i][j];
	gnt();
	gst();
	gr();
	return solve();
}