#include <fstream>

using namespace std;
ifstream f("fractii.in");
ofstream g("fractii.out");

int n , sol[1000005];
long long sum;

int main()
{
    int i , j;
    f>>n;
    for(i=1; i<=n ; ++i) 
       sol[i]=i-1;
    for(i=2; i<=n ; ++i)
    {
       sum=sum+sol[i];
       for(j=2*i; j<=n; j+=i)
       sol[j]=sol[j]-sol[i]; 
    }
    sum=sum*2+1;
    g<<sum;
    return 0;
}