#include <iostream>
#include <stdio.h>
#include <vector>
#include <string>
#include <algorithm>
#include <functional>

#define REP(i,n) for(int i=0;i<n;i++)
#define maxi(a,b) (((a) > (b)) ? (a) : (b))
#define mini(a,b) (((a) > (b)) ? (a) : (b))
#define OUTL(a) cout << (a) << endl

using namespace std;

int main() {
	//cin.tie(0);
	//ios::sync_with_stdio(false);
	/********************************************************/
	long long min = 1;
	long long max = 1000000000;
	long long mid = (min + max) / 2;
	long long midbef = 0;
	long long in;

	for (int i = 0; i < 100; i++) {

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

		cin >> in;

		if (abs(max - min) <= 1) {
			cout << "! " << mid << endl;
			return 0;
		}

		if (in) {
			min = mid;
		}
		else {
			max = mid;
		}

		midbef = mid;
		mid = (min + max) / 2;

	}

	/********************************************************/

	return 0;
}