#define _USE_MATH_DEFINES
#define _CRT_SECURE_NO_WARNINGS
#include<stdio.h>
#include<string>
#include<iostream>
#include<cctype>
#include<cstdio>
#include<vector>
#include<stack>
#include<queue>
#include <algorithm>
#include<math.h>
#include<set>
#include<map>
#include <sstream>
#include<iomanip>

//#include<bits/stdc++.h>


using namespace std;

int main() {
	long long int a=0, b = 1000000000;
	while (a != b) {
		long long int x = a + b;
		x /= 2;
		cout << "? " << x << endl;
		long long int y;
		cin >> y;
		if (y == 1) {
			a = x;
			if (b == a + 1)break;
		}
		else {
			b = x;
			if (b == a + 1)break;
		}
		
	}
	cout <<"! "<< a << endl;
	return 0;
}