#include <fstream>

using namespace std;

ifstream f("fractii.in");
ofstream g("fractii.out");
int a[1000050];
long long nr=0;
int main()
{
     int i,j,n;
    f>>n;
    for(i=1;i<=n;i++)
        a[i]=i-1;
    for(i=2;i<=n;i++)
        for(j=i*2;j<=n;j+=i)
            a[j]=a[j]-a[i];
    for(i=2;i<=n;i++)
        nr+=a[i];
    g<<2*nr+1<<"\n";
    return 0;
}