#include <iostream>
#include <fstream>

using namespace std;

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

int a[1000001];
unsigned long long nr;

int main()
{
    int n,i,j;
    f>>n;

        for(i=1;i<=n;i++)
        a[i]=i-1;

        for(i=2;i<=n;i++)
        {
            for(j=2*i;j<=n;j=j+i)
                a[j]=a[j]-a[i];
            nr=nr+2*a[i];
        }
        nr++;

        g<<nr;

    return 0;
}