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