#include <fstream>
using namespace std;
ifstream f ("fractii.in");
ofstream g ("fractii.out");
long long sol;
int rez[1000003], n;
int main ()
{
    f>>n;
    for(int i=1;i<=n;i++) rez[i]=i-1;
    for(int i=2;i<=n;i++)
    {
        for(int j=2*i;j<=n;j+=i)
            rez[j]-=rez[i];
        sol=(long long)sol+rez[i];
    }
    g<<2*sol+1;
    return 0;
}