#include<cstdio>
#include<cmath>
using namespace std;
int euler(int n)
{
    int phi,f,p,lim;
    phi=n;
    lim=(int)sqrt((double)n);
    f=2;
    while(f<=lim && n>1)
    {
        p=0;
        while(n%f==0)
        {
            p++;
            n=n/f;
        }
        if(p>0)
            phi=phi/f*(f-1);
        f++;
    }
    if(n>1)
        phi=phi/n*(n-1);
    return phi;
}
int main()
{
    freopen("fractii.in","r",stdin);
    freopen("fractii.out","w",stdout);
    int n,val,valt=0,i;
    scanf("%d",&n);
    for(i=1;i<=n;i++)
    {
        val=euler(i);
        valt=valt+val;
    }
    valt=valt*2-1;
    printf("%d\n",valt);
    return 0;
}