#include <bits/stdc++.h>
using namespace std;

#define SZ(a) (int)a.size()
#define ALL(a) a.begin(), a.end()
#define FOR(i, a, b) for (int i = (a); i<(b); ++i)
#define RFOR(i, b, a) for (int i = (b)-1; i>=(a); --i)
#define MP make_pair
#define PB push_back
#define F first
#define S second

typedef long long LL;
typedef pair<int, int> PII;
typedef vector<int> VI;

int main()
{
	//ios::sync_with_stdio(false);
	//cin.tie(0);
	LL pw = 1;
	while (true) {
		cout << "? " << pw << endl;
		LL x;
		cin >> x;
		if (x != pw) {
			cout << "! " << pw - x << endl;
			return 0;
		}
		pw *= 2;
	}
	return 0;
}