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