var n,p,q,nr,pp,qq:longint;
    f,g:text;
begin
         assign(f,'fractii.in');
         reset(f);
         read(f,n);
         close(f);
        nr:=2*n-1;
        p:=1;
        q:=1;
  repeat
            p:=p+1;
            pp:=p;
            q:=q+1;
            qq:=p;
           while p<=n do
             begin
        if p mod q>0 then nr:=nr+1;
            p:=p+1;
             end;
            p:=pp;
          while q<=n do
             begin
          if q mod p>0 then nr:=nr+1;
          q:=q+1;
              end;
            q:=qq;
    until p=n;
    assign(g,'fractii.out');
    rewrite(g);
    write(g,nr);
    close(g);
end.