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

int main() {
	int ok = 1, ng = 1e9 + 1;
	while (abs(ok - ng) > 1) {
		int mid = (ok + ng) / 2;
		cout << "? " << mid << endl;
		int r; cin >> r;
		if (r) ok = mid;
		else ng = mid;
	}
	cout << "! " << ok << endl;
}