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

public class Program
{
    static public void Main(string[] args)
    {
        Console.WriteLine("? 64");
        string s = Console.ReadLine();
        int min = -1, max = -1;
        switch (s)
        {
            case "-1":
                max = 64;
                min = 10;
                break;
            case "1":
                max = (int)1e9 + 1;
                min = 65;
                break;
            case "0":
                Console.WriteLine("! 64");
                return;
        }

        for (int i = 1; ; i++)
        {
            int mid = (min + max) / 2;
            Console.WriteLine($"? {mid - i}");
            s = Console.ReadLine();
            switch (s)
            {
                case "-1":
                    max = mid - 1;

                    break;
                case "1":

                    min = mid + 1;
                    break;
                case "0":
                    Console.WriteLine($"! {mid}");
                    return;
            }
        }
    }
}