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