#include <bits/stdc++.h>
using namespace std;
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  int N, D, H;
  cin >> N >> D >> H;
  if (D == 1) {
    if (N == 2)
      cout << "1 2\n";
    else
      cout << "-1\n";
    return 0;
  } else if (D > 2 * H) {
    cout << "-1\n";
    return 0;
  }
  int prev = 1, cur = H + 2;
  for (int i = 0; i < H; i++) {
    cout << prev << " " << 2 + i << endl;
    prev = 2 + i;
  }
  if (D > H) {
    prev = 1;
    for (int i = 0; i < D - H; i++) {
      cout << prev << " " << H + 2 + i << endl;
      prev = H + 2 + i;
    }
    cur = H + 2 + D - H - 1 + 1;
  }
  while (cur <= N) {
    cout << H << " " << cur << endl;
    cur++;
  }
  return 0;
}
