#include <fstream>

using namespace std;

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

    int n,i,j,nr=0;
    short int a[1000001];
    fin>>n;
    for(i=1;i<=n;i++)
    a[i]=i-1;
    for(i=2;i<=n;i++)
    {
        for(j=i*2;j<=n;j=j+i)
        {
            a[j]=a[j]-a[i];
        }
    }
    for(i=2;i<=n;i++)
    {
        nr=nr+a[i]*2;
    }
    nr=nr+1;
    fout<<nr;
    fin.close ();
    fout.close ();
    return 0;

}