using System;
using System.Collections.Generic;
class Program
{
    //http://yukicoder.me/submissions/36416　←参考にさせていただきました
    static void Main(string[] args)
    {
        int max = 100000000 + 1;
        int min = 0;
        bool finish = true;

        int count = 0;
        while (count < 30 && max - min > 10)
        {
            count ++;
            int mid = (min + max) / 2;
            Console.WriteLine("? " + mid);
            int answer = int.Parse(Console.ReadLine());
            if (answer == 1)//↑にある
            {
                min = mid;
            }
            else if(answer == -1)//↓にある
            {
                max = mid;
            }
            else //ちょうどやで
            {
                Console.WriteLine("! "+ (mid-1));
                finish = false;
                break;
            }
        }
        int ans = max - min;
        while (finish)
        {
            Console.WriteLine("? " + ans);
            int answer = int.Parse(Console.ReadLine());
            if (answer == 1)
            {
                if (ans >= 5)
                {
                    ans -= 5;
                }
                else
                {
                    ans = 0;
                }
            }
            else if(answer == 0)
            {
                Console.WriteLine((ans == 0) ? "! " + 0.ToString() : "! " + (ans-1));
                break;
            }
        }
        Console.ReadKey();
    }
}