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