#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, d, h, i;
  while (scanf("%d %d %d", &n, &d, &h) == 3) {
    if (d > 2 * h || h > n - 1 || d > n - 1 || h > d) {
      printf("-1\n");
      continue;
    }
    if (d == h && h == 1 && n != 2) {
      printf("-1\n");
      continue;
    }
    for (i = 1; i <= h; i++) {
      printf("%d %d\n", i, i + 1);
    }
    if (h == n - 1) continue;
    int j = i - 1;
    i++;
    if (d == h && h != n - 1) {
      for (; i <= n; i++) {
        printf("%d %d\n", j, i);
      }
      continue;
    }
    printf("%d %d\n", 1, i);
    for (; i <= d; i++) {
      printf("%d %d\n", i, i + 1);
    }
    i++;
    for (; i <= n; i++) {
      printf("%d %d\n", 1, i);
    }
  }
  return 0;
}
