#include <fstream>
#include <cmath>
using namespace std;
int a[1000001];
int main()
{
    ifstream in("fractii.in");
    ofstream out("fractii.out");
    int n,i,j,nr=0;

    in>>n;
    for(i=2;i<=n;i++)
        a[i]=i-1;
    for(i=2;i<=n;i++)
    {
        for(j=2*i;j<=n;j=j+i)
            a[j]-=a[i];
        nr+=2*a[i];
    }
    nr++;
    out<<nr;

    return 0;
}