#include <fstream>
#include <iostream>
using namespace std;

long n;
long phi[1000001];
void cit()
{
    ifstream f;
    f.open("fractii.in");
    f>>n;
    f.close();
}
long sum()
{
    long s=0;
    for (long i=1;i<=n;i++)
        s+=phi[i];
    return s;
}
int main()
{
    cit();
    for (long i=1;i<=n;i++)
        phi[i]=i-1;
    for (long i=1;i<=n;i++)
        for (long j=2*i;j<=n;j+=i)
            phi[j]-=phi[i];
    ofstream g;
    g.open("fractii.out");
    g<<2*sum()+1;
    g.close();
    return 0;
}