#include<iostream>
using namespace std;
int timer = 0;
int ask(int Y){
	cout << "? " << Y << endl;
	int res;
	cin >> res;
    timer++;
	return res;
}
int main(){
    int res = ask(100);
    int min = 10;
    int max = 1e9;
    int mid;
    if(res == 0){
        cout << "! " << 100 << endl;
    }
    else if(res < 0) max = 99;
    else min = 101;
    while(1){
        mid = min + (max-min)/2;
        res = ask(mid - timer);
        if(res == 0){
            cout << "! " << mid << endl;
            break;
        }
        else if(res == 1){
            min = mid+1;
        }
        else{
            max = mid-1;
        }
    }
	return 0;
}