#include <bits/stdc++.h>
using namespace std;
const int INF = 1e9 + 23;
const int MOD = 1e9 + 9;
const int MAXN = 2e3 + 100;
int main() {
  ios_base::sync_with_stdio(0);
  int n, d, h;
  cin >> n >> d >> h;
  if (n <= d || d < h || d > 2 * h) {
    cout << "-1\n";
    return 0;
  }
  if (d > h && n < d + 1) {
    cout << "-1\n";
    return 0;
  }
  if (h == 1 && d == 1 && n > 2) {
    cout << "-1\n";
    return 0;
  }
  stringstream ss;
  for (int i = 1; i <= h; ++i) {
    ss << i << " " << (i + 1) << "\n";
  }
  for (int i = h + 1, last = 1; i <= d; ++i) {
    ss << last << " " << (i + 1) << "\n";
    last = i + 1;
  }
  int from = (h == 1 ? 1 : 2);
  for (int i = d + 2; i <= n; ++i) {
    ss << from << " " << i << "\n";
  }
  cout << ss.str();
  return 0;
}
