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