#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, d, h, x = 1;
  cin >> n >> d >> h;
  if (d > 2 * h || (d == 1 && n != 2)) {
    cout << -1;
    return 0;
  }
  if (d == h) x = 2;
  for (int i = 1; i <= h; i++) cout << i << ' ' << i + 1 << endl;
  if (d - h > 0) {
    cout << x << ' ' << h + 2 << endl;
    for (int i = 0; i < d - h - 1; i++)
      cout << h + 2 + i << ' ' << h + 3 + i << endl;
  }
  for (int i = 1; i < n - d; i++) cout << x << ' ' << d + 1 + i << endl;
  return 0;
}
