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