#include <fstream>
using namespace std;
ifstream in("fractii.in");
ofstream out("fractii.out");
long long a,n,d[1010],nr;
long long r;
bool v[1010];
long long Phi(long long n)
{
    long long r=n;
    for(long long i=1;d[i]*d[i]<=n&&i<=nr;++i)
    {
        if(n%d[i]==0)
        {
            while(n%d[i]==0)
                n/=d[i];
            r=r-r/d[i];
        }
    }
    if(n>1)
    	r=r-r/n;
    return r;
}
int main()
{
    for(long long i=2;i<=1000;++i)
    {
        if(v[i]==false)
        {
            d[++nr]=i;
            for(long long j=i;j*i<=1000;++j)
                v[i*j]=true;
        }
    }
    in>>n;
    for(long long i=1;i<=n;++i)
        r+=Phi(i);
    out<<r*2-1;
    return 0;
}