#include <iostream>
#include <fstream>
#include <cmath>
using namespace std;
ifstream fin("fractii.in");
ofstream fout("fractii.out");
int n,r,a,b,i,j,nr,c[1000001];
int main()
{
    fin>>n;
    for(i=1;i<=n;i++)
        c[i]=i-1;
    for(i=2;i<=n;i++)
    {
        for(j=i+i;j<=n;j+=i)
            c[j]-=c[i];
    }
    for(i=1; i<=n; i++)
    {
        nr=nr+2*c[i];
    }
    fout<<nr+1;
    return 0;
}