3
2 1 1
 6
6 2 6 2 4 2
 2
1 2
 8
2 1 2 2 6 5 6 6
 18
2 3 4 5 2 7 8 9 10 7 11 12 14 15 13 17 18 18
 7
1 2 3 4 5 6 7
 7
4 3 2 6 3 5 2
 7
7 5 3 1 2 1 5
 7
1 6 4 4 5 6 7

1
2 2 1  0
6 2 6 2 4 2  1 
1 1 
 2 
2 2 2 2 6 2 6 6 
 5 
2 3 4 5 11 7 8 9 10 11 11 11 14 15 11 17 18 11 
 6 
1 1 1 1 1 1 1 
 1
4 3 3 6 3 5 2  1
7 5 3 1 3 1 5  4 
1 6 4 1 1 1 1 

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