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