#include <fstream>
using namespace std;
ifstream in("fractii.in");
ofstream out("fractii.out");
int a,n;
long long r;
int Phi(int n)
{
    int r=n;
    for(int i=2;i*i<=n;++i)
    {
        if(n%i==0)
        {
            while(n%i==0)
                n/=i;
            r=r-r/i;
        }
    }
    if(n>1)
    	r=r-r/n;
    return r;
}
int main()
{
    in>>n;
    for(int i=1;i<=n;++i)
        r+=Phi(i);
    out<<r*2-1;
    return 0;
}