#include <bits/stdc++.h>
using namespace std;
const int MOD = 1e9 + 7;
long long power(long long a, long long b) {
  long long ret = 1;
  while (b) {
    if (b & 1) ret *= a;
    a *= a;
    if (ret >= MOD) ret %= MOD;
    if (a >= MOD) a %= MOD;
    b >>= 1;
  }
  return ret;
}
long long inv(long long x) { return power(x, MOD - 2); }
const int N = 1e5 + 5;
int n;
int main() {
  std::ios::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  cin >> n;
  if (n <= 5) {
    cout << "-1\n";
  } else {
    cout << "1 2\n1 3\n1 4\n";
    for (int i = 5; i <= n; i++) {
      cout << "2 " << i << "\n";
    }
  }
  for (int i = 1; i + 1 <= n; i++) cout << i << " " << (i + 1) << "\n";
}
