program p1;
var i,j,nr,n,a,p,b:longint;
    f,g:text;
begin
     assign(f,'fractii.in');reset(f);
     assign(g,'fractii.out');rewrite(g);
     read(f,n);
     nr:=1;
     for i:=2 to n do
         begin
              a:=1;
              b:=1;
              j:=i;
              p:=2;
              while j<>1 do
                    begin
                        if j mod p=0 then begin
                                          while j mod p=0 do  j:=j div p;
                                          a:=a*(p-1);
                                          b:=b*p;
                                          end;
                         p:=p+1;
                    end;
             nr:=nr+2*a*i div b;
          end;
     writeln(g,nr);
     close(f);
     close(g);
end.