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