#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, d, h;
  cin >> n >> d >> h;
  if (h * 2 < d) {
    cout << -1;
    return 0;
  }
  if (d == 1) {
    if (n >= 3) {
      cout << -1;
      return 0;
    }
    if (n == 2) {
      cout << 1 << ' ' << 2;
      return 0;
    }
  }
  for (int i = 2; i <= h + 1; i++) {
    cout << i << ' ' << i - 1 << endl;
  }
  int b = d - h;
  if (b > 0) {
    cout << 1 << ' ' << h + 2 << endl;
    for (int i = h + 3; i <= d + 1; i++) {
      cout << i << ' ' << i - 1 << endl;
    }
  }
  int hd = 1;
  if (b == 0) {
    hd = 2;
  }
  for (int i = d + 2; i <= n; i++) {
    cout << hd << ' ' << i << endl;
  }
  return 0;
}
