using System;
using System.Linq;
using System.Text;
namespace Yuki
{
    class Program
    {
        static void Main(string[] args)
        {
            Console.WriteLine("? 100");
            string a = Console.ReadLine();
            if (a == "0")
            {
                Console.WriteLine("! 100");
            }
            else if (a == "-1")
            {
                aa();
            }
            else
            {
                bb();
            }
        }

        static void aa()
        {
            int c = 1;
            while (true)
            {
                Console.WriteLine("? 9");
                if (Console.ReadLine() == "0")
                {
                    Console.WriteLine("! {0}", 9 + c);
                    break;
                }
                else
                {
                    c++;
                }
            }
        }

        static void bb()
        {
            int ma = 1000000000 - 1;
            int mi = 100;
            int c = 1;
            int y = -1;
            int r = ma;
            while (ma - mi > 5)
            {
                y = (ma + mi) / 2;
                string a = Console.ReadLine();
                if (a == "0")
                {
                    Console.WriteLine("! {0}", y + c);
                    return;
                }
                else if (a == "-1")
                {
                    ma = y - 1;
                    mi -= 1;
                    c++;
                }
                else
                {
                    ma -= 1;
                    mi = y - 1;
                    c++;
                }
            }

            while (true)
            {
                Console.WriteLine("? {0}", mi - 1);
                if (Console.ReadLine() == "0")
                {
                    Console.WriteLine("! {0}", mi - 1 + c);
                    break;
                }
                else
                {
                    c++;
                }
            }
        }
    }
}