#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int n, d, h;
  cin >> n >> d >> h;
  if (d > 2 * h) return cout << -1, 0;
  if (d == 1) return cout << (n > 2 ? "-1" : "1 2"), 0;
  for (int i = 2; i <= h + 1; i++) cout << i - 1 << " " << i << endl;
  for (int i = 0; i < d - h; i++)
    cout << (i == 0 ? 1 : h + i + 1) << " " << h + i + 2 << endl;
  for (int i = d + 2; i <= n; i++) cout << h << " " << i << endl;
  return 0;
}
