#include<algorithm>
#include<cmath>
#include<cstdio>
#include<functional>
#include<iomanip>
#include<iostream>
#include<map>
#include<queue>
#include<set>
#include<string>
#include<utility>
#include<vector>

using namespace std;
typedef long long ll;
const ll mod = 1000000007;
#define rep(i,n) for(int i=0;i<n;i++)
#define repl(i,s,e) for(int i=s;i<e;i++)
#define reple(i,s,e) for(int i=s;i<=e;i++)
#define revrep(i,n) for(int i=n-1;i>=0;i--)
#define all(x) (x).begin(),(x).end()

int main()
{	
	int lb = -1;
	int ub = 1000000001;

	rep(i, 100)
	{
		int mid = (lb + ub) / 2;

		cout << "? " << mid << endl;

		int d;
		cin >> d;

		if (d >= 1)
		{
			lb = mid;
		}
		else
		{
			ub = mid;
		}
	}

	cout << "! " << lb << endl;

	return 0;
}