#include <bits/stdc++.h>
using namespace std;
const int N = 110000;
int main() {
  ios_base::sync_with_stdio(0);
  int n, d, h;
  cin >> n >> d >> h;
  if (d == 1) {
    if (n > 2)
      cout << -1 << endl;
    else
      cout << "1 2" << endl;
    return 0;
  }
  if (d - h > h) {
    cout << -1 << endl;
    return 0;
  }
  if (d == h) {
    for (int i = 2; i <= d + 1; i++) cout << i - 1 << " " << i << endl;
    for (int i = d + 2; i <= n; i++) cout << i << " " << 2 << endl;
    return 0;
  }
  for (int i = 2; i <= h + 1; i++) cout << i - 1 << " " << i << endl;
  cout << 1 << " " << h + 2 << endl;
  for (int i = h + 3; i <= h + 2 + d - h - 1; i++)
    cout << i - 1 << " " << i << endl;
  for (int i = h + 2 + d - h; i <= n; i++) cout << 1 << " " << i << endl;
  return 0;
}
