#include <iostream>
#include <fstream>
using namespace std;
int cmmdc(int a,int b)
{
    int r=a%b;
    while(r)
    {
        a=b;
        b=r;
        r=a%b;
    }
    return b;
}

int n,v[1000004],i,j;
int main()
{
    ifstream f("fractii.in");
    ofstream g("fractii.out");
    f>>n;
    int nr=1;
    for(i=1;i<=n;i++)
        v[i]=i-1;
    for(i=2;i<=n;i++)
    {
        j=2*i;
        while(j<=n)
        {
            v[j]=v[j]-v[i];
            j=j+i;
        }
    }
    for(i=1;i<=n;i++)
        nr=nr+2*v[i];
    g<<nr;
}