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