#include<stdio.h>
#include<iostream.h>
#include<math.h>
long n;
long f(long k)
{
    long ck,i,d=1;
    ck=k-1;
    char v[1000000]={0};
    if(k==2)
        return 1;
    if(!(k%2))
        {
            while(2*d<k)
            {
                v[2*d]=1;
                ck--;
                d++;
            }
        }
    for(i=3;i<sqrt(k);i+=2)
    {
        d=1;
        if(!(k%i))
            while(i*d<k)
            {
                v[2*d]=1;
                ck--;
                d++;
            }
    }
    return ck;
}
int main()
{
    long i;
    long long fract=0;
    freopen("fractii.in","r",stdin);
    freopen("fractii.out","w",stdout);
    cin>>n;
    for(i=2;i<n;i++)
        fract+=f(i);
    fract*=2;fract++;
    cout<<fract;
    return 0;
}