#include <bits/stdc++.h>
using namespace std;
const int inf = 1e9;
int main() {
  int n, d, h;
  cin >> n >> d >> h;
  if (h * 2 < d || h > n || d > n || h > d || n < d + 1 ||
      (h == 1 && d == 1 && (n != 2)))
    cout << -1;
  else {
    if (h == 1) {
      for (int i = 2; i <= n; i++) cout << 1 << ' ' << i << endl;
      return 0;
    }
    for (int i = 1; i <= h; i++) cout << i << ' ' << i + 1 << endl;
    for (int i = 1; i <= d - h; i++)
      cout << ((i == 1) ? 1 : i + h) << ' ' << i + h + 1 << endl;
    for (int i = 0; i < n - d - 1; i++) cout << 2 << ' ' << n - i << endl;
  }
  return 0;
}
