package main;

import java.util.Scanner;

public class Main {

    public static void main(String[] args) throws Exception {

        Scanner sc = new Scanner(System.in);

        long max = 1000000000;
        long min = 1;

        for (int i = 0; i < 100; i++) {
            
            long num = (min + max) / 2;
            System.out.print("? " + num);

            if (sc.nextInt() == 1) {

                min = num;
            } else {
                max = num;
            }
            
            if(min == max){
                System.out.println("! " + max);
            }
        }
    }
}