program ciur;
  var s,nr,di,fin,n:longint;f,g:text;
  begin
  assign(f,'ciur.in');reset(f);
  assign(g,'ciur.out');rewrite(g);
  read(f,n);;nr:=3;s:=2;n:=n-3;
  while n>0 do begin
  if fin=1 then inc(s);fin:=1;di:=1;n:=n-1;inc(nr);
  repeat
  inc(di);
  if nr mod di=0 then
  fin:=0;
  until (di=trunc(sqrt(nr)))or(fin=0);
  end;
  write(g,s);
    close(f);
    close(g);
    end.