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 min = 1;
        int max = 1000000001;
        while (min != max)
        {
            int A = (min + max) / 2;
            Console.WriteLine("? {0}", A);
            int r = int.Parse(Console.ReadLine());
            if (r == 1)
            {
                max = A;
            }
            else
            {
                min = A + 1;
            }
        }
        Console.WriteLine("! {0}", min);
    }
}