#include <bits/stdc++.h>
using namespace std;
int main() {
  long long int n, d, h;
  cin >> n >> d >> h;
  if (d > (2 * h))
    cout << "-1" << endl;
  else if (d == 1 && h == 1 && n > 2)
    cout << "-1" << endl;
  else {
    for (int i = (h + 1); i >= 2; i--) {
      cout << i << " " << i - 1 << endl;
    }
    long long int k = (d - h - 1);
    long long int x = n, f = 0, fl = 0;
    while (k > 0) {
      cout << x << " " << x - 1 << endl;
      x--;
      k--;
      fl = 1;
    }
    for (int i = (h + 2); i <= (n - (max(f, (d - h)))); i++) {
      cout << i << " " << h << endl;
    }
    if (d - h >= 1) cout << x << " " << 1 << endl;
  }
}
