#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, d, h, i;
  cin >> n >> d >> h;
  if (n >= 3 && (d == 1 || d > 2 * h))
    cout << -1 << endl;
  else {
    for (i = 1; i <= h; i++) cout << i << " " << i + 1 << endl;
    for (i = 1; i <= d - h; i++)
      cout << (i == 1 ? 1 : i + h) << " " << i + h + 1 << endl;
    for (i = d + 2; i <= n; i++) cout << h << " " << i << endl;
  }
}
