#include<iostream>
#include<fstream>
using namespace std;
ifstream in("fractii.in");
ofstream out("fractii.out");

int main()
{
    long long n;
    in>>n;
    long long phi[n+1];
    for(long long i=1;i<=n;i++)
        phi[i]=i-1;
    for(long long i=1;i<=n;i++)
        for(long long j=i*2;j<=n;j=j+i)
            phi[j]=phi[j]-phi[i];
    long long s=0;
    for(int i=1;i<=n;i++)
        s=s+phi[i];
    out<<s*2+1;
}