use feature say;
$|=1;
say"? 100";++$n;
if(<><1){
	do{
		say"? 1";++$n;
	}while<>>0;
	say"! ",$n;
}else{
	$a=100;
	$b=1e9+1;
	while($a<$b-1){
		say"? ",($c=$a+$b>>1)-$n++;
		<><0?$b:$a=$c;
	}
	say"! ",$a;
}