func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int n, i, j;     cin >> n;     if (n == 1) {       cout << 0 << endl;       return 0;     }     if (n == 2) {       cout <<  1 n1 2 n ;       return 0;     }     cout << (n / 2) * (n / 2 + n % 2) << endl;     for (i = 1; i <= n / 2; i++)       for (j = n / 2 + 1; j <= n; j++) cout << i <<     << j << endl;     return 0;   }   