var con,cont,i,b,N:longint;
    i,o:text;
begin
 assign(i,ciur.in); reset(i);
 assign(o,ciur.our); rewrite(o);
 read(N);
 for i:=2 to N do begin
  for b:=1 to i do begin
  if i mod b=0 then cont:=cont+1;
  end;
  if cont=2 then con:=con+1;
 end;
 write(con);
 close(ciur.in);
 close(ciur.out);
end.