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