#include <bits/stdc++.h>
using namespace std;
int n, d, h, at;
int main() {
  ios::sync_with_stdio(false);
  cin.tie(0);
  cin >> n >> d >> h;
  if ((n != 2 && d == 1) || d > h + h) {
    cout << -1 << '\n';
    return 0;
  }
  for (int i = 1; i <= h; i++) {
    cout << i << ' ' << i + 1 << '\n';
  }
  int add = d - h, st = 1;
  for (int i = 1; i <= add; i++) {
    cout << st << ' ' << h + i + 1 << '\n';
    st = h + i + 1;
  }
  add = n - 1 - d;
  if (st == 1) st = h + 1;
  if (d == h)
    at = 2;
  else
    at = 1;
  for (int i = 0; i < add; i++) {
    ++st;
    cout << at << ' ' << st << '\n';
  }
  return 0;
}
