module main;
// https://sugarknri.hatenablog.com/entry/2016/05/20/205444 より
// インタラクティブ問題、二分探索
import std;

int ask(int m)
{
	writefln("? %d", m);
	stdout.flush;
	return readln.chomp.to!int;
}

void main()
{
	int ret, t = 0, l = 10, u = 10 ^^ 9 + 1, m = 32;
	ret = ask(32);
	while (ret) {
		if (ret == 1)
			l = m;
		else
			u = m;
		t++;
		m = (u + l) / 2;
		ret = ask(m - t);
	}
	writefln("! %d", m);
	stdout.flush;
}