sub f{
	if($#_){
		my@a=f(splice@_,@_/2);
		@b=f(splice@_);
		push@_,shift@{print("? $a[0] $b[0]\n")*<>?\@a:\@b}while@a*@b;
		push@_,@a,@b;
	}
	@_;
}
@a=f++$|..<>;
print"!
$#a
@a"