using System;
class Program
{
    static void Main(string[] args)
    {
        //出力は　
        int max = 1000000000;
        int b = max / 2;
        int ask = max / 2;

        for (int i = 0; i < 100; i++)
        {
            Console.WriteLine("? " + ask);
            b /= 2;
            if (int.Parse(Console.ReadLine()) == 1)
            {
                ask += b;
            }
            else
            {
                ask -= b;
            }

            if (b == 0)
            {
                ask -= 13;
                while (true)
                {
                    Console.WriteLine("? " + ask);
                    if (int.Parse(Console.ReadLine()) == 1) ask++;
                    else
                    {
                        Console.WriteLine("! " + (ask - 1));
                        break;
                    }
                }
            }
        }
    }
}