#include <iostream>
#include <math.h>
#include <fstream>
using namespace std;

int main()
{
    ifstream fin("fractii.in");
    ofstream fou("fractii.out");

    int n;
    long long int nr;
    fin>>n;
    int vec[n];
    for(int i=2;i<=n;++i)
        vec[i]=i-1;

    for(int i=2;i<=n;++i)
    {
        nr += vec[i];
        for(int j=2*i;j<=n;j += i)
            vec[j]-=vec[i];
    }
    nr=2*nr+1;
    fou<<nr;
    //fout.close();
    return 0;
}