#include <iostream>
#include <fstream>

using namespace std;

ifstream f("fractii.in");
ofstream g("fractii.out");

int prime[1000001];
long long sum;
int main()
{
    int n, p, i;
    f>>n;
    for(i=1;i<=n;i++)
        prime[i]=i-1;
    for(p=2;p<=n;p++)
    {
        sum+=prime[p];
        for(i=p*2;i<=n;i+=p)
            prime[i]=prime[i]-prime[p];
    }
    sum=sum*2+1;
    g<<sum;
    return 0;
}