#include <iostream>
#include <fstream>
using namespace std;
ifstream in("fractii.in");
ofstream out("fractii.out");
int main()
{
    int n,d,s;
    in>>n;
    s=n*n;
    for (int i=2;i<=n;i++)
    {
        d=2;
        while (d<=i)
        {
            if (i%d==0)
            {
                out<<i<<" "<<d<<endl;
                if (d!=i)
                    s--;
                s--;
            }
            d++;
        }
    }
    out<<s;
}