#define _USE_MATH_DEFINES
#include <algorithm>
#include <cstdio>
#include <fstream>
#include <functional>
#include <iostream>
#include <cfloat>
#include <climits>
#include <cstdlib>
#include <cstring>
#include <cmath>
#include <map>
#include <queue>
#include <random>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <time.h>
#include <vector>
using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> i_i;
typedef pair<ll, int> ll_i;
typedef pair<double, int> d_i;
typedef pair<ll, ll> ll_ll;
typedef pair<double, double> d_d;
struct edge { int v, w; };

ll MOD = 1000000007;
ll _MOD = 1000000009;
double EPS = 1e-10;

int main() {
	int lb = 0, ub = 1000000001;
	while (ub - lb > 1) {
		int mid = (lb + ub) / 2;
		cout << "? " << mid << endl;
		int x; cin >> x;
		if (x) lb = mid;
		else ub = mid;
	}
	cout << "! " << lb << endl;
}