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