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