#include <bits/stdc++.h>
using namespace std;
int main() {
  long long n, d, h, i, s, t;
  cin >> n >> d >> h;
  vector<pair<long long, long long> > v;
  if (d > (2 * h) || d < h) {
    cout << -1;
    return 0;
  }
  if (d == h && h == 1 && n != 2) {
    cout << -1;
    return 0;
  }
  t = 1;
  for (i = 0; i < h; i++) {
    v.push_back({t, t + 1});
    t++;
  }
  t++;
  if (d > h) {
    v.push_back({1, t});
    for (i = h + 1; i < d; i++) {
      v.push_back({t, t + 1});
      t++;
    }
    t++;
  }
  while (t <= n) {
    v.push_back({h, t});
    t++;
  }
  for (i = 0; i < n - 1; i++) {
    cout << v[i].first << " " << v[i].second << endl;
  }
  return 0;
}
