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 min = 1;
        int max = (int) 1e9;

        while (min + 1 != max) {

            int tmp = (min + max) / 2;
            System.out.println("? " + tmp);

            int t = sc.nextInt();

            if (t == 1) {
                min = tmp;
            } else {
                max = tmp;
            }
        }

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