#include <iostream>
#include <fstream>
using namespace std;

ifstream fin("fractii.in");
ofstream fout("fractii.out");

int main()
{
    long long n,i,total,j,temp;
    fin>>n;total=0;
    for(i=2;i<=n;i++)
    {
        total+=n;
        long long divizor=1, temp=i;
        do
        {
         divizor++;
         if (temp%divizor==0)
         {
            while ((temp%divizor==0)&&(temp!=1))
                temp=temp/divizor;
            if(divizor%2==0)
                total-=n/divizor;
            else
                if(i%2!=0)
                    total=total-n/divizor;
                else
                    total=total-n/divizor+(n/divizor+1)/2;
        }
        }
        while ((temp!=1)&&(divizor<=i));
    }

    fout<<total+n<<"\n";
        return 0;
}