#include<fstream>
using namespace std;
int main()
{

    long n,rez=0,i,j;
    ofstream out("fractii.out");
    ifstream in("fractii.in");
    in>>n;
    in.close();
    long v[n+1];
    for (i = 2 ; i<=n ; ++i)
        v[i] = i-1;
    for(i = 2 ; i <= n ; ++i)
    {
        rez+=v[i];
        for( j = 2*i ; j<=n ; j+=i)
            v[j] -= v[i];
    }
    out<<2*rez+1;
    out.close();
    return 0;
}