#include <iostream>
#include <algorithm>
#include <functional>
#include <string>
#include <climits>
#include <vector>
#include <numeric>
#include <complex>
#include <map>
#include <bitset>
using namespace std;

//#define __int64 long long
#define long __int64
#define REP(i,a,b) for(int i=a;i<b;i++)
#define rep(i,n) REP(i,0,n)
const int Vecy[4] = {0,-1,0,1};
const int Vecx[4] = {1,0,-1,0};


int main(){
	bool in;
	int min=0;
	int max=1000000000;
	int h;
	
	while(min + 1 <= max){
		h = (min + max) / 2;
		cout << "? " << h << endl;
		cin >> in;
		if(in){		//より大きい
			min = h + 1;
		}else{
			max = h;
		}
	}
	
	cout << "! " << min << endl;
    
    return 0;
}