#include <fstream>
using namespace std;
int a[1000005];
long long nr=0;
int main()
{
    ifstream f("fractii.in");
    ofstream g("fractii.out");
    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";
    f.close();
    g.close();
    return 0;
}