#include <bits/stdc++.h>
using namespace std;
void IOS() {
  ios::sync_with_stdio(false);
  cout.precision(10);
  cout << fixed;
}
const long long MOD = 1e9 + 7;
const long long mx = 1e5 + 5;
long long i, j, k;
long long gcd(long long x, long long y) {
  if (y == 0) return x;
  return gcd(y, x % y);
}
long long lcm(long long x, long long y) { return (x * y) / gcd(x, y); }
int32_t main() {
  IOS();
  long long n;
  cin >> n;
  if (n < 6) {
    cout << -1 << "\n";
    for (long long i = 2; i <= n; i++) {
      cout << 1 << " " << i << "\n";
    }
  } else if (n >= 6) {
    for (long long i = 2; i <= 4; i++) {
      cout << 1 << " " << i << "\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";
    }
  }
  return 0;
}
