#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(0);
  int n, d, h;
  cin >> n >> d >> h;
  if (n < d + 1 || (d > 2 * h) || d < h || (n > 2 && h == 1 && d == 1))
    cout << -1;
  else {
    for (int i = 1; i < h + 1; ++i) cout << i << " " << i + 1 << "\n";
    int j = h + 2;
    int s = 1;
    n -= (h + 1);
    d -= h;
    while (n > 0 && d > 0) {
      cout << s << " " << j << "\n";
      s = j;
      j++;
      n--;
      d--;
    }
    while (n > 0) {
      cout << h << " " << j++ << "\n";
      n--;
    }
  }
  return 0;
}
