#include <bits/stdc++.h>
using namespace std;
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  int a, b, c;
  cin >> a >> b >> c;
  if (a == 2) {
    cout << 1 << " " << 2;
    return 0;
  }
  if (b == 1 || b > c * 2) {
    cout << -1;
    return 0;
  }
  int vertex = 2;
  for (int i = 0; i < c; i++, a--) {
    cout << vertex - 1 << " " << vertex << '\n';
    vertex++;
  }
  bool first = 1;
  for (int i = 0; i < b - c; i++, a--) {
    if (first)
      cout << 1 << " " << vertex << '\n';
    else
      cout << vertex - 1 << " " << vertex << '\n';
    vertex++;
    first = 0;
  }
  a--;
  while (a--) {
    cout << (c == 1 ? 1 : 2) << " " << vertex << '\n';
    vertex++;
  }
}
