#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  int n, d, h;
  cin >> n >> d >> h;
  if (d == 1) {
    if (h == 1 && n == 2) {
      cout << 1 << " " << 2 << endl;
    } else
      cout << -1 << endl;
    return 0;
  }
  if (d + 1 > n || h + 1 > n) {
    cout << -1 << endl;
    return 0;
  }
  if (d < h || d > 2 * h) {
    cout << -1 << endl;
    return 0;
  }
  int x = 1;
  int rt = 1;
  for (int i = 1; i <= h; i++) {
    rt = x;
    int l = x;
    int r = ++x;
    cout << l << " " << r << endl;
  }
  d -= h;
  if (d > 0) {
    rt = 1;
    int l = 1;
    int r = ++x;
    cout << l << " " << r << endl;
    for (int i = 2; i <= d; i++) {
      rt = x;
      int l = x;
      int r = ++x;
      cout << l << " " << r << endl;
    }
  }
  if (n > x) {
    n -= (x);
    for (int i = 1; i <= n; i++) {
      int l = rt;
      int r = ++x;
      cout << l << " " << r << endl;
    }
  }
}
