#include <bits/stdc++.h>
using namespace std;
long long c, n, d, h;
signed main() {
  ios::sync_with_stdio(false);
  cin.tie(NULL), cout.tie(NULL);
  cin >> n >> d >> h;
  if (d > 2 * h || d == 1 && n - 2) return cout << -1 << endl, 0;
  for (long long i = 1; i <= h; ++i) {
    c++;
    cout << c << " " << c + 1 << endl;
  }
  c++;
  if (d == h)
    while (c < n) {
      c++;
      cout << 2 << " " << c << endl;
    }
  else {
    c++;
    cout << 1 << " " << c << endl;
    for (long long i = 1; i < d - h; ++i) {
      cout << c << " " << c + 1 << endl;
      c++;
    }
    while (c < n) {
      c++;
      cout << 1 << " " << c << endl;
    }
  }
  return cout << endl, 0;
}
