#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, d, h;
  scanf("%d %d %d", &n, &d, &h);
  if (!((d + 1) / 2 <= h && n >= d + 1) || (d == 1 && n > 2)) {
    puts("-1");
    return 0;
  }
  int cur = 2;
  for (int i = 0; i < h; ++i) {
    printf("%d %d\n", cur - 1, cur);
    ++cur;
  }
  for (int i = 0; i < d - h; ++i) {
    printf("%d %d\n", i == 0 ? 1 : cur - 1, cur);
    ++cur;
  }
  while (cur <= n) {
    printf("%d %d\n", d == h ? 2 : 1, cur);
    ++cur;
  }
}
