#include<fstream>
using namespace std;

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

long long  p[1000009],n,i,j,sol=0;

int main()
{

    fin>>n;
    for (i=1;i<=n;i++) p[i]=i-1;
    for (i=2;i<=n;i++)
    {
        j=2*i;
        while (j<=n)
        {
            p[j]-=p[i];
            j+=i;
        }
    }
    for (i=1;i<=n;i++)
        sol+=p[i];
    fout<<sol*2+1;
   fin.close();fout.close();
    return 0;
}