#include <bits/stdc++.h>
using namespace std;
int n;
int A[200100] = {0, 1, 2, 1, 3, 1, 4, 2, 5, 2, 6};
int con;
int main() {
  scanf("%d", &n);
  con = 10;
  if (n <= 5)
    printf("-1\n");
  else {
    for (int i = 7; i <= n; i++) {
      con++;
      A[con] = 2;
      con++;
      A[con] = i;
    }
    for (int i = 1; i <= con; i += 2) {
      printf("%d %d\n", A[i], A[i + 1]);
    }
  }
  for (int i = 2; i <= n; i++) {
    printf("1 %d\n", i);
  }
  return 0;
}
