func_code_string: #include <bits/stdc++.h>   using namespace std;   const long long mod = 1000000007;   long long rowNum[] = {-1, 0, 0, 1};   long long colNum[] = {0, -1, 1, 0};   int main() {     int n, d, h;     cin >> n >> d >> h;     if (d > n - 1 || d < h || d > 2 * h || (n > 2 && h < 2 && d == h)) {       cout <<  -1 n ;       return 0;     }     int prev = 0;     for (long long i = 1; i < h + 1; i++) {       cout << prev + 1 <<     << i + 1 << endl;       prev = i;     }     if (d == h) {       for (long long i = h + 1; i < n; i++) {         cout <<  2   << i + 1 << endl;       }       return 0;     }     prev = 0;     for (long long i = h + 1; i < d + 1; i++) {       cout << prev + 1 <<     << i + 1 << endl;       prev = i;     }     for (long long i = d + 1; i < n; i++) {       cout <<  1   << i + 1 << endl;     }   }   