#include <iostream>
#include <vector>
#include <cstdio>
#include <sstream>
#include <map>
#include <string>
#include <algorithm>
#include <queue>
#include <cmath>
#include <set>
using namespace std;

int main(){
	//int x;
	//cin >> x;

	bool small = false;
	{
		int res;
		cout << "? 1024" << endl;

		//cerr << x-- << endl;

		cin >> res;

		if(res == 0){
			cout << "! " << 1024 << endl;
			return 0;
		}

		small = res < 0;
	}

	int lb = 0;
	int ub = small?1024:1000000001;

	int turn = 1;
	while((ub-lb) > 1){
		int mid = (0LL + lb + ub) / 2;
		cout << "? " << mid << endl;


		//cerr << x-- << endl;


		int res;
		cin >> res ;
		if(res == 0){
			cout << "! " << mid + turn << endl;
			return 0;
		}

		if(res < 0){
			ub = mid;
		}else{
			lb = mid;
		}

		ub -= 1;
		lb -= 1;
		if(lb < 0) lb = 0;

		turn++;
	}

	cerr << lb << " " << ub << endl;
	cout << "! " << lb+turn << endl;

	return 0;
}