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