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;

        while (min != max) {

            long num = (min + max) / 2;
            System.out.println("? " + num);

            if (sc.nextInt() == 1) {
                min = num;
            } else {
                max = num;
            }
        }

        System.out.println("! " + max);
    }
}