#include<iostream>
#include<fstream>
using namespace std;
int main()
{
    ofstream g("fractii.out");
     ifstream f("fractii.in");
    long n,i,j,v[10000010],z;
    long long nr;
    f>>n;
    for (i=2; i<=n; i++)
    v[i]=i-1;
    nr=0;
    for (i=2; i<=n; i++)
    {
        for (j=2*i; j<=n; j+=i)
        v[j]-=v[i];
        nr+=v[i];
    }
    z=2*nr+1;
    g<<z;
    return 0;
}