#include <bits/stdc++.h>
using namespace std;
int k[100000], used[1000000];
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int n, d, h;
  cin >> n >> d >> h;
  if (d > h * 2) {
    cout << -1;
    exit(0);
  }
  if (d == 1 && n - 1 > d) {
    cout << -1;
    exit(0);
  }
  int i;
  for (i = 1; i <= h; i++) {
    cout << i << " " << i + 1 << "\n";
  }
  if (d == h) {
    for (i++; i <= n; i++) {
      cout << 2 << " " << i << "\n";
    }
    exit(0);
  }
  cout << 1 << " " << i + 1 << "\n";
  i++;
  for (i; i <= d; i++) {
    cout << i << " " << i + 1 << "\n";
  }
  for (i++; i <= n; i++) {
    cout << 1 << " " << i << "\n";
  }
}
