package main;

import java.util.*;

public class Main {

    public static void main(String[] args) {
        // TODO 自動生成されたメソッド・スタブ
        Scanner sc = new Scanner(System.in);
        int a = 1;
        int b = (int) 1e9;
        while (a != b) {
            int c = (a + b) / 2;
            System.out.println("? " + c);
            int t = sc.nextInt();
            if (t == 1) {
                a = c;
            } else {
                b = c;
            }
        }
        
        System.out.println("! " + a);
    }
}