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