#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  scanf("%d", &n);
  if (n < 6)
    printf("-1\n");
  else {
    printf("1 2\n2 3\n2 4\n1 5\n1 6\n");
    for (int i = 7; i <= n; ++i) printf("%d %d\n", 1, i);
  }
  for (int i = 2; i <= n; ++i) {
    printf("%d %d\n", 1, i);
  }
  return 0;
}
