#include <bits/stdc++.h>
using namespace std;
int main() {
  long int i, n, d, h, a[100045] = {0}, y, z;
  cin >> n >> d >> h;
  if (d > n - 1 || h < (d + 1) / 2)
    cout << "-1" << endl;
  else if (n >= 3 && d <= 1)
    cout << "-1" << endl;
  else {
    y = 2;
    a[h] = 1;
    for (i = 0; i <= n - 1; i++) {
      if (a[i] == 0) {
        a[i] = y;
        y++;
      }
    }
    y = 0;
    while (d != 1) {
      cout << a[y] << " " << a[y + 1] << endl;
      y++;
      d--;
    }
    z = a[y];
    while (y < n - 1) {
      cout << z << " " << a[y + 1] << endl;
      y++;
    }
  }
  return 0;
}
