using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.Text;
using System.Text.RegularExpressions;
using System.Linq;


class Magatro
{
    static void Main()
    {
        int plus = 1 << 30;
        int ans = 0;
        for(int i = 0; i < 30; i++)
        {
            plus /= 2;
            int w = ans + plus;
            Console.WriteLine("? {0}",w);
            if (Console.ReadLine() == "0")
            {
                ans = w;
            }
        }
        Console.WriteLine("! {0}", ans + 1);
    }
}