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;
        while (max - min > 20)
        {
            int mid = (min + max) / 2;
            Console.WriteLine("? " + mid);
            if (int.Parse(Console.ReadLine()) == 1)
            {
                max = mid;
            }
            else
            {
                min = mid;
            }
        }
        int ans = max - min;
        bool waiting = false;
        while(true)
        {
            Console.WriteLine("? " + ans);
            if (int.Parse(Console.ReadLine()) == 1)//↓にある
            {
                if (waiting)
                {
                    Console.WriteLine("! " + (ans - 2));
                }
                else
                {
                    ans -= 5;
                    waiting = false;
                }
            }
            else
            {
                waiting = true;
            }
        }
    }
}