def I():return int(input())
def MAP():return map(int,input().split())
def MAPs():return map(str,input().split())
def LI(): return list(map(int,input().split()))
def TPL(): return tuple(map(int,input().split()))
def S():return input()
from collections import defaultdict,Counter,deque
from copy import deepcopy
from heapq import heapify,heappop,heappush
from bisect import bisect_left,bisect_right
from itertools import accumulate,product,permutations,combinations,combinations_with_replacement
from math import gcd,ceil,floor,factorial,sqrt,pi,sin,cos,tan,radians,exp
import time
import random
inf=float('inf');mod=998244353;Mod=10**9+7
dydx=[(1,0),(0,1),(-1,0),(0,-1)]

ok=-1;ng=10**9+1
while ng-ok>1:
    mid=(ok+ng)//2
    print('?',mid)
    if I()==1:
        ok=mid
    else:
        ng=mid
print('!',ok)