#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  long long n;
  cin >> n;
  if (n < 6) {
    cout << -1 << "\n";
  } else {
    printf("1 2\n");
    printf("1 3\n");
    printf("1 4\n");
    for (long long i = 5; i <= n; i++) {
      cout << 2 << " " << i << "\n";
    }
  }
  for (long long i = 2; i <= n; i++) {
    cout << 1 << " " << i << "\n";
  }
}
