#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  scanf("%d", &n);
  if (n <= 5)
    printf("-1\n");
  else {
    printf("1 2\n");
    for (int i = 3; i <= n; i++)
      if (i & 1)
        printf("1 %d\n", i);
      else
        printf("2 %d\n", i);
  }
  for (int i = 2; i <= n; i++) printf("%d %d\n", 1, i);
  return 0;
}
