def main():
    def ask(m):
        print("?",m)
        ret=int(input())
        if ret==0:
            print("!",m+cnt)
            exit()
        return ret

    cnt=0
    if ask(100)==-1:
        cnt+=1
        while 1:
            ask(8)
            cnt+=1

    l,r=95,10**9+1
    cnt=1
    while l+1<r:
        m=(l+r)//2
        res=ask(m)
        if res==1:l=m
        if res==-1:r=m
        l-=1
        r-=1
        cnt+=1

main()