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