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