#include<stdio.h>
#include<math.h>
int main()
{
    int n,i,s=0,j,p,ci;
    freopen("fractii.in","r",stdin);
    freopen("fractii.out","w",stdout);
    scanf("%d",&n);
    for(i=2;i<n;i++)
    {
        p=1;
        ci=i;
        for(j=2;j<=sqrt(i);j++)
            if(ci%j==0)
            {
                while(ci%j==0)
                    ci=ci/j;
                p=p*(1-1/j);
            }
        if(p==1)
            p=(1-1/i);
        s=s+p*i;
    }
    s=2*s+1;
    printf("%d",s);
    return 0;
}