var n,i,j,r:integer;
begin
 assign(input,'ciur.in');reset(input);
 assign(output,'ciur.out');rewrite(output);
 readln(n);
 for i:=1 to n do begin
  for j:=2 to trunc (sqrt(i)) do
  if i mod j>0 then inc(r);
                  end;
  write(r);
 close(input);close(output);
end.