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;
        int help = 0;

        while (help == 100)
        {
            int mid = (min + max) / 2;
            Console.WriteLine("? " + (mid - help));
            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
            {
                if ((mid - help - 1) < 0) Console.WriteLine("! " + 0);
                else Console.WriteLine("! "+ (mid - help - 1));
                break;
            }
            help++;
        }
        
    }
}