#include <bits/stdc++.h>
using namespace std;
const int mod = 1e9 + 7;
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  ;
  int n, d, h;
  cin >> n >> d >> h;
  if (h < (d + 1) / 2 || (d < 2 && n > 2)) {
    cout << -1 << endl;
    return 0;
  }
  int other = 1;
  int extra = 1;
  if (h == d) {
    extra = 2;
  }
  int start = 1;
  while (start < h + 1) {
    cout << start << " " << start + 1 << endl;
    d--;
    start++;
  }
  start++;
  while (d) {
    cout << other << " " << start << endl;
    other = start;
    start++;
    d--;
  }
  while (start <= n) {
    cout << extra << " " << start << endl;
    start++;
  }
}
