#include <algorithm>
#include <iostream>
#include <fstream>
using namespace std;

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

int v[1000001];

int main ()
{
    int n, i, j, S=0;
    in>>n;

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

    for(i=2; 2*i<=n; i++)
    {
        for (j=2*i; j<=n; j=j+i)
            v[j]=v[j]-v[i];
    }
    for (i=1; i<=n; i++) S=S+v[i];

        out<<S*2+1  ;
        return 0;
}