#include <bits/stdc++.h>
using namespace std;
vector<pair<int, int> > edge;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  int n, d, h;
  cin >> n >> d >> h;
  if (d == 1) {
    if (n == 2) {
      cout << 1 << " " << 2 << endl;
      return 0;
    }
    cout << -1 << endl;
    return 0;
  }
  vector<int> v(d + 1);
  int ind = 1;
  for (int i = 0; i < d + 1; i++) {
    if (i != h) {
      v[i] = ind++;
    } else {
      v[i] = 0;
    }
  }
  if (d - h > h) {
    cout << -1;
    return 0;
  }
  for (int i = 0; i < ((int)(v.size())) - 1; i++) {
    edge.push_back(make_pair(v[i], v[i + 1]));
  }
  for (int i = ind; i < n; i++) {
    edge.push_back(make_pair(v[1], i));
  }
  for (int i = 0; i < ((int)(edge.size())); i++) {
    cout << edge[i].first + 1 << " " << edge[i].second + 1 << "\n";
  }
  return 0;
}
