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