#include <fstream>
using namespace std;

int main()
{
    long long n,d,e,p,x,S=0,i;
    ifstream f("fractii.in");
    ofstream g("fractii.out");
    f>>x;
    for(i=1;i<=x;i++)
    {

        n=i;
        d=2;
        p=n;
        while(n>1 and d*d<=n)
            {
                e=0;
                while(n%d==0)
                    {
                        e++;
                        n=n/d;
                    }
                if(e) p=p*(d-1)/d;
                d++;
            }
        if(n>1) p=p*(n-1)/n;
        S=S+p;
    }
    S=2*S-1;
    g<<S;
    return 0;
}