#include <fstream>
using namespace std;

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

long long a[1000005],n;

void init()
{
    a[1] = 1;
    for(int i=2; i<=n; ++i)
        a[i] = i-1;
}

void scad()
{
    long long sum=0;
    for(int i=2; i<=n; ++i)
    {
        sum += 2*a[i];
        for(int j=i+i; j<=n; j+=i)
            a[j] -= a[i];
    }
    g<<sum+1;
}

int main()
{
    f>>n;
    init();
    scad();
    return 0;
}