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