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