#include <bits/stdc++.h>
using namespace std;
const int N = 1e4;
int n, d, h;
int main() {
  ios::sync_with_stdio(0), cin.tie(0);
  cin >> n >> d >> h;
  if (d - h > h) {
    cout << -1 << endl;
    return 0;
  }
  if (d == 1) {
    if (n >= 3) {
      cout << -1 << endl;
      return 0;
    }
  }
  int cur = 1;
  for (int i = 1; i <= h; i++) {
    cout << cur << ' ' << cur + 1 << endl;
    cur++;
  }
  int now = 1;
  for (int i = 1; i <= d - h; i++) {
    cout << now << ' ' << cur + 1 << endl;
    now = ++cur;
  }
  for (int i = 1; i <= n - d - 1; i++) cout << h << ' ' << ++cur << endl;
  return 0;
}
