#include <stdio.h>
#include <bits/stdc++.h>
#include <atcoder/all>
using namespace atcoder;
using mint = modint1000000007;
using namespace std;
#define rep(i,n) for(int i=0;i<(n);i++)
#define Inf 1000000001


int main(){
	int ok = 0;
	int ng = 1000000001;
	
	while(ng-ok>1){
		int mid = (ok+ng)/2;
		cout<<"? "<<mid<<endl;
		int r = 0;
		cin>>r;
		if(r)ok = mid;
		else ng  = mid;
	}
	cout<<"! "<<ok<<endl;
	
	return 0;
}