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

int main(){
	int l = 0, r = 1000000001;
	while(r - l > 1) {
		int m = (l + r) / 2;
		cout << "? " << m;
		int a;
		cin >> a;
		cin.clear();
		if(a == 0) {
			r = m;
		}
		else {
			l = m;
		}
	}
	cout << "! " << l << endl;
}