#include <fstream>
using namespace std;
ifstream fin("fractii.in");ofstream fout("fractii.out");
int n,frac[1000001],j,i;unsigned long long cate;
int main()
{
    fin>>n;
    for(i=2;i<=n;i++)
        frac[i]=i-1;
    for(i=2;i<=n;i++)
    {
        for(j=i<<1;j<=n;j+=i)
            frac[j]-=frac[i];
        cate+=frac[i];
    }
    fout<<2*cate+1;
    return 0;
}