#include <bits/stdc++.h>
using namespace std;
int n, d, k;
int main() {
  while (~scanf("%d%d%d", &n, &d, &k)) {
    if (d < k || n < d + 1 || (d == 1 && n != 2) || d > 2 * k) {
      printf("-1\n");
      continue;
    }
    if (k == d) {
      int single = n - d - 1;
      int pos = 1;
      for (int i = 1; i <= d; i++) {
        printf("%d %d\n", pos, pos + 1);
        pos++;
      }
      pos++;
      for (int i = 1; i <= single; i++) {
        printf("2 %d\n", pos);
        pos++;
      }
      continue;
    }
    int single = n - d - 1;
    int pos = 2;
    int k2 = d - k;
    for (int i = 1; i <= single; i++) {
      printf("1 %d\n", pos);
      pos++;
    }
    printf("1 %d\n", pos);
    for (int i = 1; i <= k - 1; i++) {
      printf("%d %d\n", pos, pos + 1);
      pos++;
    }
    if (k2 != 0) {
      pos++;
      printf("1 %d\n", pos);
      for (int i = 1; i <= k2 - 1; i++) {
        printf("%d %d\n", pos, pos + 1);
        pos++;
      }
    }
  }
  return 0;
}
