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