#include <bits/stdc++.h>

using namespace std;

int biggest_stadium(int n, vector<vector<int>> f) {
    vector<vector<int>> pr_sum(n + 1, vector<int>(n + 1));
    for (int i = 0; i < n; ++i) {
        for (int j = 0; j < n; ++j) {
            f[i][j] ^= 1;
            pr_sum[i + 1][j + 1] = pr_sum[i + 1][j] + pr_sum[i][j + 1] - pr_sum[i][j] + f[i][j];
        }
    }
    if (pr_sum[n][n] == n * n - 1) {
        for (int i = 0; i < n; ++i) {
            for (int j = 0; j < n; ++j) {
                if (!f[i][j]) {
                    return n * n - min(i + 1, n - i) * min(j + 1, n - j);
                }
            }
        }
    }
    vector<vector<int>> ll(n, vector<int>(n, -1)), rr(n, vector<int>(n, n)), dd(n, vector<int>(n, n));
    for (int i = n - 1; i >= 0; --i) {
        for (int j = 0; j < n; ++j) {
            if (!f[i][j]) {
                ll[i][j] = j;
                dd[i][j] = i;
            } else {
                if (j > 0) {
                    ll[i][j] = ll[i][j - 1];
                }
                if (i + 1 < n) {
                    dd[i][j] = dd[i + 1][j];
                }
            }
        }
        for (int j = n - 1; j >= 0; --j) {
            if (!f[i][j]) {
                rr[i][j] = j;
            } else if (j + 1 < n) {
                rr[i][j] = rr[i][j + 1];
            }
        }
    }
    bool check = true;
    auto get = [&](int i1, int j1, int i2, int j2) {
        return pr_sum[i2][j2] - pr_sum[i1][j2] - pr_sum[i2][j1] + pr_sum[i1][j1];
    };
    for (int i = 0; i < n; ++i) {
        for (int j = 0; j < n; ++j) {
            if (!f[i][j]) {
                continue;
            }
            int l = ll[i][j], r = rr[i][j], d = dd[i][j];
            if (get(i, 0, i + 1, l + 1) || get(i, d, i + 1, n) || get(i, r, i + 1, n)) {
                check = false;
            }
            if (l > -1 && d < n) {
                if (pr_sum[n][l] - pr_sum[d + 1][0]) {
                    check = false;
                }
            }
            if (r < n && d < n) {
                if (pr_sum[n][n] - pr_sum[d + 1][n] - pr_sum[n][r + 1] + pr_sum[d + 1][r + 1]) {
                    check = false;
                }
            }
        }
    }
    if (check) {
        return pr_sum[n][n];
    } else {
        return pr_sum[n][n] - 1;
    }
}