#define _CRT_SECURE_NO_WARNINGS
#define _USE_MATH_DEFINES
#include <stdio.h>
#include <algorithm>
#include <utility>
#include <functional>
#include <cstring>
#include <queue>
#include <stack>
#include <math.h>
#include <iterator>
#include <vector>
#include <string>
#include <set>
#include <math.h>
#include <iostream> 
#include<map>
#include <list>
#include <typeinfo>
using namespace std;
#define REP(a,b) for(long long a = 0;a < b;++a)
int main() {
	long long x_low = 1;
	long long x_high = 1000000000;
	int cnt = 0;
	while (cnt != 100) {
		cnt++;
		long long hoge = (x_high+x_low) / 2;
		cout << "? "<< hoge << endl;
		int a = 0;
		cin >> a;
		if (a == 0) {
			x_high = hoge;
		}
		else {
			x_low = hoge;
		}
	}
	cout << "! " << x_low << endl;
}