#include <fstream>
#include <cmath>
using namespace std;
int a[1000001];
int main()
{
    ifstream f("fractii.in");
    ofstream g("fractii.out");
    int n,i,j;
    unsigned long long nr=0;
    f>>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[j]-a[i];
        nr=nr+2*a[i];
    }
    nr++;
    g<<nr;
    f.close();
    g.close();
    return 0;
}