#include <iostream>
#include <fstream>
using namespace std;
ifstream f("fractii.in");
ofstream g("fractii.out");
long n,k,i,j;
int main()
{       f>>n;
        if(n==1) {cout<<1;
                    return 0;    }
        if(n%2==0)k=n+n/2*n/2;
            else k=n+n/2*n/2+1;

     for (i=3;i<=n;i+=2)
            {
                if(n%i==0)k=(n-n/i)+k;
                    else k=(n-n/i)+k-1;

                for(j=2;j<=n;j+=2)
                    if(j%i==0) k-=1;
            }
        g<<k;
    return 0;
}