#include <bits/stdc++.h>
using namespace std;
int n, d, h, cur = 1;
int main() {
  scanf("%d%d%d", &n, &d, &h);
  if (d > 2 * h || (h == 1 && d == 1 && n > 2)) return cout << -1 << endl, 0;
  for (int i = 0; i < h && n > 1; i++) {
    cout << cur << " ";
    cout << ++cur << endl;
    n--;
  }
  int x = cur - 1;
  cur++;
  n--;
  if (n) {
    if (d == h)
      cout << x << " " << cur << endl;
    else
      cout << "1 " << cur << endl;
  }
  for (int i = 1; i < d - h && n > 1; i++) {
    cout << cur << " ";
    cout << ++cur << endl;
    n--;
  }
  cur++;
  for (int i = 1; i < n; i++) cout << x << " " << cur++ << endl;
  return 0;
}
