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