#include "soccer.h"
#include<bits/stdc++.h>
#define all(v) v.begin(), v.end()
using namespace std;
const int N = 2010;
int n;
bool a[N][N];
vector<int> arr[N];
int check_valid() {
for(int col = 0; col < n; col++) {
for(int row = 0; row < n; row++) if (a[row][col] == 0) arr[col].push_back(row);
}
int st = 0;
while (st < n && arr[st].empty()) st++;
if (st == n) return 0;
int ed = st;
while (ed < n && !arr[ed].empty()) ed++; ed--;
for(int i = 1; i < st; i++) if (!arr[i].empty()) return 0;
for(int i = ed + 1; i < n; i++) if (!arr[i].empty()) return 0;
for(int i = st; i <= ed; i++) if (arr[i].size() != arr[i].back() - arr[i][0] + 1) return 0;
int cnt = 0;
for(int i = st; i <= ed; i++) cnt += arr[i].size();
int L = max(arr[st][0], arr[ed][0]);
int R = min(arr[st].back(), arr[ed].back());
while (st <= ed) {
if (arr[st].size() <= arr[ed].size()) {
if (arr[st][0] <= L && arr[st].back() >= R) {
L = arr[st][0];
R = arr[st].back();
st++;
}
else return 0;
}
else {
if (arr[ed][0] <= L && arr[ed].back() >= R) {
L = arr[ed][0];
R = arr[ed].back();
ed--;
}
else return 0;
}
}
return cnt;
}
namespace sub4 {
const int N = 51;
int pref[N][N];
int dp[N][N][N][N];
int solve() {
for(int i = 0; i < n; i++) {
pref[i][0] = a[i][0];
for(int j = 1; j < n; j++) pref[i][j] = pref[i][j - 1] + a[i][j];
}
auto check = [&] (int i, int l, int r) {
int sum = pref[i][r];
if (l > 0) sum -= pref[i][l - 1];
return sum == 0;
};
int ans = 0;
// cout << check(1, 1, 2) << endl;
memset(dp, -61, sizeof(dp));
for(int i = 0; i < n; i++) {
for(int u = 0; u < n; u++) for(int v = u; v < n; v++) if (check(i, u, v)) dp[i][i][u][v] = v - u + 1;
}
for(int x = n - 1; x >= 0; x--) for(int y = x; y <= n; y++) {
for(int u = 0; u < n; u++) for(int v = u; v < n; v++) {
for(int _u = 0; _u <= u; _u++) for(int _v = v; _v < n; _v++) {
if (y + 1 < n && check(y + 1, u, v)) dp[x][y + 1][u][v] = max(dp[x][y + 1][u][v], dp[x][y][_u][_v] + v - u + 1);
if (x > 0 && check(x - 1, u, v)) dp[x - 1][y][u][v] = max(dp[x - 1][y][u][v], dp[x][y][_u][_v] + v - u + 1);
}
ans = max(ans, dp[x][y][u][v]);
}
}
return ans;
}
}
namespace AC {
const int N = 2010, M = 2e3 * 2e3 * 2 + 10;
int b[N], L[N], R[N], dp[M], trans[2][M];
int close[N];
vector<int> open[N], lst[N], event[2][N];
tuple<int, int, int, int> rect[M];
int solve() {
cerr << 1.0 * clock() / CLOCKS_PER_SEC << endl;
// for(int i = 1; i <= n; i++) {
// for(int j = 1; j <= n; j++) cout << a[i][j] << " "; cout << endl;
// }
int m = 0;
auto histogram = [&] () {
stack<int> st;
for(int i = 1; i <= n; i++) {
while (!st.empty() && b[st.top()] >= b[i]) st.pop();
L[i] = st.empty() ? 0 : st.top();
st.push(i);
}
while (!st.empty()) st.pop();
for(int i = n; i >= 1; i--) {
while (!st.empty() && b[st.top()] >= b[i]) st.pop();
R[i] = st.empty() ? n + 1 : st.top();
st.push(i);
}
};
for(int i = 1; i <= n; i++) {
for(int j = 1; j <= n; j++) {
if (a[i][j]) b[j] = 0;
else b[j]++;
}
histogram();
for(int j = 1; j <= n; j++) if (b[j]) {
rect[++m] = make_tuple(i - b[j] + 1, i, L[j] + 1, R[j] - 1);
}
}
for(int j = 1; j <= n; j++) b[j] = 0;
for(int i = n; i >= 1; i--) {
for(int j = 1; j <= n; j++) {
if (a[i][j]) b[j] = 0;
else b[j]++;
}
histogram();
for(int j = 1; j <= n; j++) if (b[j]) {
rect[++m] = make_tuple(i, i + b[j] - 1, L[j] + 1, R[j] - 1);
}
}
for(int i = 1; i <= m; i++) {
lst[get<1> (rect[i]) - get<0> (rect[i])].push_back(i);
}
cerr << 1.0 * clock() / CLOCKS_PER_SEC << endl;
for(int delta = 0; delta < n; delta++) {
for(int &i : lst[delta]) {
int x1, x2, y1, y2; tie(x1, x2, y1, y2) = rect[i];
event[0][x2].emplace_back(i);
event[1][x1].emplace_back(i);
}
}
cerr << 1.0 * clock() / CLOCKS_PER_SEC << endl;
for(int i = 1; i <= n; i++) for(int t = 0; t < 2; t++) {
for(auto &j : event[t][i]) {
int x1, x2, y1, y2; tie(x1, x2, y1, y2) = rect[j];
open[y1].push_back(j);
close[y2]++;
}
stack<int> st;
for(int j = 1; j <= n; j++) {
for(auto &k : open[j]) {
trans[t][k] = st.empty() ? 0 : st.top();
st.push(k);
} open[j].clear();
while (close[j]--) st.pop();
close[j] = 0;
}
}
int ans = 0;
for(int delta = 0; delta < n; delta++) {
for(int &i : lst[delta]) {
int x1, x2, y1, y2; tie(x1, x2, y1, y2) = rect[i];
dp[i] = (x2 - x1 + 1) * (y2 - y1 + 1);
if (trans[0][i]) { // top
int j = trans[0][i];
dp[i] = max(dp[i], dp[j] + (get<0> (rect[j]) - x1) * (y2 - y1 + 1));
} // bottom
if (trans[1][i]) {
int j = trans[1][i];
dp[i] = max(dp[i], dp[j] + (x2 - get<1> (rect[j])) * (y2 - y1 + 1));
}
ans = max(ans, dp[i]);
}
}
cerr << 1.0 * clock() / CLOCKS_PER_SEC << endl;
return ans;
}
}
int biggest_stadium(int N, std::vector<std::vector<int>> F)
{
n = N;
for(int i = 0; i < n; i++) for(int j = 0; j < n; j++) a[i][j] = F[i][j];
// if (n <= 30) return sub4::solve();
// if (n <= 500) return sub5::solve();
for(int i = 1; i <= n; i++) for(int j = 1; j <= n; j++) a[i][j] = F[i - 1][j - 1];
return AC::solve();
}
#ifdef ngu
int main()
{
freopen ("task.inp", "r", stdin);
freopen ("task.out", "w", stdout);
int N;
assert(1 == scanf("%d", &N));
std::vector<std::vector<int>> F(N, std::vector<int>(N));
for (int i = 0; i < N; i++)
{
for (int j = 0; j < N; j++)
{
assert(1 == scanf("%d", &F[i][j]));
}
}
fclose(stdin);
int res = biggest_stadium(N, F);
printf("%d\n", res);
fclose(stdout);
return 0;
}
#endif // ngu
