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