#include <iostream>
#include <fstream>

using namespace std;

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

int phi(int n)
{
    int r = n , d = 2;
    while(n > 1)
    {
        if(n % d == 0)
        {
            r = r / d * (d - 1);
            while(n % d == 0)
                n /= d;
        }
        d ++;
        if(d * d > n)
            d = n;
    }
    return r;
}

int main()
{
    int n;
    unsigned long long s=0;
    fin >> n;
    for(int i =1;i<=n;++i)
        s=s+phi(i);
    fout << s*2-1;
    return 0;
}