#include <bits/stdc++.h>
using namespace std;
int main() {
  int n, a, i = 1;
  cin >> n;
  if (n <= 5)
    cout << -1 << endl;
  else if (n == 6) {
    cout << "1 2\n1 3\n1 4\n3 5\n3 6" << endl;
  } else if (n == 7) {
    cout << "1 2\n1 3\n1 4\n1 5\n3 6\n3 7" << endl;
  } else {
    cout << "1 2" << endl;
    cout << "1 3\n2 4\n2 5\n3 6\n4 7\n4 8" << endl;
    a = n - 8;
    while (a > 0) {
      cout << 4 << " " << 8 + i << endl;
      i++;
      a--;
    }
  }
  for (int i = 2; i <= n; i++) {
    cout << 1 << " " << i << endl;
  }
}
