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