var n,i,cn,j,pr:longint;
   f,g:text;
begin
assign(f,'ciur.in');
assign(g,'ciur.out');
reset(f); rewrite(g);
read(f,n);
for i:=2 to n do begin
cn:=0;
for j:=1 to i do
if i mod j=0 then inc(cn);
if cn=2 then inc(pr);
end;
write(g,pr);
close(f);
close(g);
end.