#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, h, d;
  cin >> n >> d >> h;
  if (d > 2 * h) {
    cout << -1 << endl;
    return 0;
  }
  if (d == h) {
    if (h == 1 && n > 2) {
      cout << -1 << endl;
      return 0;
    }
    for (int i = 1; i <= h; ++i) cout << i << ' ' << i + 1 << endl;
    if (h + 1 < n) {
      for (int i = h + 2; i <= n; ++i) cout << 2 << ' ' << i << endl;
    }
    return 0;
  }
  for (int i = 1; i <= h; ++i) cout << i << ' ' << i + 1 << endl;
  cout << 1 << ' ' << h + 2 << endl;
  for (int i = h + 2; i <= d; ++i) cout << i << ' ' << i + 1 << endl;
  for (int i = d + 2; i <= n; ++i) cout << 1 << ' ' << i << endl;
  return 0;
}
