#include <fstream>
using namespace std;
ifstream f("fractii.in");
ofstream g("fractii.out");
int i,j,n,v[1000001];
unsigned long long t;
int main()
{
    f>>n;
    for(i=2;i<=n;i++) v[i]=i-1;
    for(i=2;i<=n;i++)
    {
        t=t+v[i];
        for(j=2*i;j<=n;j=j+i)
            v[j]=v[j]-v[i];

    }
    t*=2;
    g<<t+1;
    return 0;
}