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