#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, d, h;
  scanf("%d%d%d", &n, &d, &h);
  if (n == 2) {
    if (d == 1 && h == 1) {
      cout << "1 2" << endl;
    } else {
      cout << -1 << endl;
    }
    return 0;
  }
  if (2 * h < d || h > d || d == 1) {
    cout << -1 << endl;
    return 0;
  }
  for (int i = 0; i < h; i++) {
    cout << i + 1 << " " << i + 2 << endl;
  }
  int prev = 1;
  int cur = h + 2;
  for (int i = 0; i < d - h; i++) {
    cout << prev << " " << cur << endl;
    prev = cur;
    cur++;
  }
  for (int i = d + 2; i < n + 1; i++) {
    cout << i << " " << ((d == h) ? 2 : 1) << endl;
  }
}
