#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, d, h;
  cin >> n >> d >> h;
  vector<pair<int, int> > g;
  if (d / 2 + d % 2 > h) {
    cout << -1;
    return 0;
  }
  if (h == 1) {
    if (n == 2) {
      cout << 1 << " " << 2 << endl;
    } else if (d > 2 || d == 1) {
      cout << -1 << endl;
    } else {
      for (int i = 1; i < n; ++i) {
        cout << 1 << " " << i + 1 << endl;
      }
    }
    return 0;
  }
  for (int i = 0; i < h; ++i) {
    g.push_back({i, i + 1});
  }
  int cur = 0;
  for (int i = 0; i < d - h; ++i) {
    g.push_back({cur, g.size() + 1});
    cur = g.size();
  }
  for (int i = 0; i < n - d - 1; ++i) {
    g.push_back({1, g.size() + 1});
  }
  for (int i = 0; i < g.size(); ++i) {
    cout << g[i].first + 1 << " " << g[i].second + 1 << endl;
  }
  return 0;
}
