#include <fstream>

using namespace std;

bool prim(int n)
{/*Functia verifica daca n este prim */

     if(n%2==0 && n!=2)
        return false;

    for(int div=3; div*div<=n; div+=2)
        if(n%div==0)
            return false;

    return true;
}

long long numarFractii(long long n)
{/*Pentru fiecare numarator verificam cate fractii nu se iau in considerare
=> cati multiplii are numaratorul pana la n (n/i) */
    long long nF=n*n - (n-1);

    for(long long i=2; i<=n/2; i++)
        if(prim(i))
            nF=nF - (n/i)*(n/i -1);

    return nF;
}

int main()
{ifstream in("fractii.in");
    int n;
    in>>n;
in.close();

ofstream out("fractii.out");
    out<<numarFractii(n);
out.close();
    return 0;
}