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

int main(void){

	long long low=1,hi=1e9,mid=0;
	while(hi > low+1){
		mid = (low + hi)/2;
		cout << "? " << mid << endl;
		int res = 0;
		cin >> res;
		if(res == 0){
			low = mid;
		}else{
			hi = mid;
		}
	}
	cout << "! " << low+1 << endl;
	return 0;
}