#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

int ans;
int ask(int y) {
	cout << "? " << y << endl;
	int res;
	cin >> res;
	/*int res;
	if (ans < y)res=-1;
	else if (ans == y)res= 0;
	else if (ans > y)res= 1;
	ans--;
	return res;*/
	return res;
}

int main()
{
	//cin >> ans;
	int cnt = 0;
	long long right=0, left=10;
	while (right==0) {
		left *= 2;
		int res = ask(left);
		if (res == -1)right = left*2;
		else if (res == 0) {
			cout << "! " << left + cnt << endl;
			return 0;
		}
		cnt++;
		//cout << ans << endl;
	}
	left /= 4;
	int mid;
	while (left < right) {
		mid = (left + right) / 2;
		int res = ask(mid);
		if (res == -1)right = mid;
		else if (res == 0) {
			cout << "! " << mid + cnt << endl;
			return 0;
		}
		else left = mid+1;
		cnt++;
		right--; left--;
		//cout << ans << endl;
	}
	//cout << mid+cnt << endl;

    return 0;
}