#include <fstream>

using namespace std;

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

int n,i,j,sum;
int nr[1000001];

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