#include <bits/stdc++.h>
using namespace std;
const double g = 10.0, eps = 1e-12;
const int N = 100000 + 10, maxn = 1200000 + 10, inf = 0x3f3f3f3f,
          INF = 0x3f3f3f3f3f3f3f3f;
int main() {
  int n;
  scanf("%d", &n);
  if (n <= 5)
    puts("-1");
  else {
    printf("1 2\n2 3\n2 4\n");
    for (int i = 5; i <= n; i++) printf("%d %d\n", 1, i);
  }
  for (int i = 2; i <= n; i++) printf("%d %d\n", 1, i);
  return 0;
}
