#include <iostream>
#include <fstream>
#include <string>
#include <cmath>
#include <vector>
#include <stdlib.h>
#include <algorithm>

using namespace std;

int nr(int a) {

    int d=2, n=0,s=1;

    while(a>1) {

        n=0;

        while (a%d==0) {

            a/=d;
            n++;
        }

        if (n>0) {

            s*=(pow(d,n)-pow(d,n-1));
            //cout<<s<<" "<<a<<" ";
        }

        if (d>2) {

        d+=2;
        }

    }
    return s;

}

int main() {

    ifstream fin("fractii.in");
    ofstream fout("fractii.out");

    int a,i,suma=0;

    fin>>a;

    suma+=1;

    for (i=2;i<=a;i++) {

        //cout<<nr(i)<<endl;
        suma+=nr(i);

    }

    suma*=2;
    suma--;

    fout<<suma;

    fin.close();
    fout.close();

	return 0;
}