#include <iostream>
using namespace std;
int main()
{
    int n;
    cin >> n;
    if (n<=5)
    puts("-1");
    else
    {
        for (int i=2;i<=4;i++)
        printf("1 %d\n",i);
        for (int i=5;i<=n;i++)
        printf("2 %d\n",i);
    }
    for (int i=2;i<=n;i++)
    printf("1 %d\n",i);
}