#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  long long n;
  cin >> n;
  long long d, h;
  cin >> d >> h;
  vector<pair<long long, long long> > v;
  int i = 1;
  long long ansd = 0;
  long long di = d;
  d -= h;
  if (d < 0 || d > h) {
    cout << -1;
    return 0;
  }
  long long plus = d;
  if (d != 0) {
    v.push_back({1, h + 2});
    d--;
  }
  for (int i = h + 2; d--; i++) {
    v.push_back({i, i + 1});
  }
  int flag = 0;
  int fl = 0;
  long long lp;
  while (i <= n) {
    if (flag < h) {
      v.push_back({i, i + 1});
      lp = i;
      flag++;
    } else {
      if (!fl) {
        fl = 1;
        i = h + 2 + plus;
      }
      if (i <= n) v.push_back({lp, i});
    }
    i++;
  }
  if (h == 1 && di == 1 && n != 2) {
    cout << -1;
    return 0;
  }
  for (auto p : v) {
    cout << p.first << " " << p.second;
    cout << '\n';
  }
}
