#include <fstream>
using namespace std;
ifstream f("fractii.in");
ofstream g("fractii.out");
int n, a[1000100];
long long s;

int main()
{
    f>>n;
    for(int i=1;i<=n;i++)
        a[i]=i-1;
    for (int i=2;i<=n;i++)
    {
        for(int j=i*2;j<=n;j+=i)
            a[j]-=a[i];
    }
    for (int i=2;i<=n;i++)
        s+=a[i];
    g<<s*2+1;
    return 0;
}