#include <bits/stdc++.h>
using namespace std;
int n, d, h;
vector<int> e[100000];
int k = 0;
int x = 0;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cin >> n >> d >> h;
  if (d > 2 * h) goto bad;
  if (d + 1 > n) goto bad;
  if (d == 1 && n > 2) goto bad;
  for (int i = 0; i < h; i++) e[i].push_back(i + 1);
  for (int i = h; i < d; i++) {
    if (i == h)
      e[0].push_back(i + 1);
    else
      e[i].push_back(i + 1);
  }
  k = d + 1;
  x = h - 1;
  for (int i = k; i < n; i++) e[x].push_back(i);
  for (int i = 0; i < n; i++)
    for (int j : e[i]) cout << i + 1 << ' ' << j + 1 << '\n';
  return 0;
bad:
  cout << -1;
  return 0;
}
