#include <bits/stdc++.h>
using namespace std;
long long mod = 1e9 + 7;
long long modpow(long long x, long long y, long long m) {
  long long z = 1;
  while (y) {
    if (y & 1) z = (z * x) % m;
    x = (x * x) % m;
    y >>= 1;
  }
  return z;
}
int egcd(int a, int b, int& x, int& y) {
  if (a == 0) {
    x = 0;
    y = 1;
    return b;
  }
  int x1, y1;
  int gcd = egcd(b % a, a, x1, y1);
  x = y1 - (b / a) * x1;
  y = x1;
  return gcd;
}
string z[2] = {"NO", "YES"};
long long modinv(long long x, long long mod) { return modpow(x, mod - 2, mod); }
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  int t = 1;
  int i, j, k, n, m;
  string s;
  while (t--) {
    cin >> n;
    if (n < 6) {
      cout << -1 << "\n";
    } else {
      cout << "1 2"
           << "\n";
      cout << "1 3"
           << "\n";
      cout << "1 4"
           << "\n";
      for (i = 5; i < n + 1; ++i) cout << "2 " << i << "\n";
    }
    for (i = 1; i < n; ++i) {
      cout << i << " " << i + 1 << "\n";
    }
  }
  return 0;
}
