var f,g:text;
     a,b,nr,n,i,p,j: longint;
 begin
 assign(f,'fractii.in');reset(f);
 assign(g,'fractii.out');rewrite(g);
 readln(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+a*2*i div b;
     end;
 writeln(g,nr);
 close(g);
 end.