#include <bits/stdc++.h>

#define rep(i, k) for (int i = 0; i < k; i++)
#define pair(x, y) make_pair((x), (y))
using namespace std;

int MAX = 1000000000;
int Q = 0;

int ask(int Y){
	cout << "? " << (Y-Q) << endl;
	Q++;
	int res;
	cin >> res;
	return res;
}

int search(int low,int high){
    int mid,res;
    while(true){
        mid = (low +high)/2;
        res = ask(mid);
        if (res == 0){
            return mid;
        }else if(res ==1){
            low = mid+1;
        }else{
            high = mid-1;
        }
    }
}

int Main(){
    int s = ask(100);
    if(s == 1) return search(101,MAX);
    if(s == 0) return 100;
    if(s == -1) return search(10,99);
}

int main(){
    int res = Main();
	cout << "! " << res << endl;

}