#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, d, h;
  cout.tie(0);
  cin.tie(0);
  cin >> n >> d >> h;
  if (d > h * 2 or (d == 1 and n > 2)) {
    cout << "-1";
    return 0;
  }
  if (d == h) {
    int cnt = 1;
    for (int i = 1; i <= h; i++) {
      cout << cnt << " " << cnt + 1 << '\n';
      cnt++;
    }
    cnt++;
    for (int i = cnt; i <= n; i++) {
      cout << 2 << " " << cnt << '\n';
      cnt++;
    }
    return 0;
  }
  int cnt = 1;
  for (int i = 1; i <= h; i++) {
    cout << cnt << " " << cnt + 1 << '\n';
    cnt++;
  }
  d -= h;
  cnt++;
  if (d) {
    cout << 1 << " " << cnt << '\n';
    d--;
    for (int i = 1; i <= d; i++) {
      cout << cnt << " " << cnt + 1 << '\n';
      cnt++;
    }
  }
  cnt++;
  for (int i = cnt; i <= n; i++) {
    cout << "1 " << cnt << '\n';
    cnt++;
  }
}
