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