func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     int n;     cin >> n;     vector<int> a, b;     for (int i = 0; i < n / 2; ++i) {       a.push_back(i);     }     for (int i = 0; i < n - n / 2; ++i) {       b.push_back(i + n / 2);     }     cout << a.size() * b.size() << endl;     for (int i = 0; i < a.size(); ++i) {       for (int j = 0; j < b.size(); ++j) {         cout << a[i] + 1 <<     << b[j] + 1 << endl;       }     }     return 0;   }   