#include <bits/stdc++.h>   int main() {     std::ios_base::sync_with_stdio(false);     std::cin.tie(nullptr);     int n;     std::cin >> n;     std::vector<std::vector<int>> a(n, std::vector<int>(n));     for (int i = 0; i < n; ++i) {       for (int j = 0; j < n; ++j) {         a[i][j] = 4 * (i % (n / 2) * (n / 2) + j % (n / 2)) + i / (n / 2) * 2 +                   j / (n / 2);       }     }     for (int i = 0; i < n; ++i) {       for (int j = 0; j < n; ++j) {         std::cout << a[i][j] <<    ;       }       std::cout <<   n ;     }     return 0;   }   