#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, d, h;
  cin >> n >> d >> h;
  if ((h + 1 + d - h > n || d > 2 * h) || (h == d && h == 1 && n > 2)) {
    cout << -1;
    return 0;
  }
  for (int i = 1; i <= h; i++) cout << i << " " << i + 1 << endl;
  int a = 1, b = h + 2;
  for (int i = 1; i <= d - h; i++) {
    cout << a << " " << b << endl;
    int temp = b;
    a = b;
    b = temp + 1;
  }
  int used = d + 1;
  a = 1;
  if (h == d) a = 2;
  while (used < n) {
    cout << a << " " << ++used << endl;
  }
  return 0;
}
