def main():
    l,r=-1,10**9+1
    cnt=1
    while l+1<r:
        m=(l+r)//2
        print("?", m)
        rep=int(input())
        if rep==1:l=m
        elif rep==-1:r=m
        else:
            print("!",m+cnt)
            break
        l=max(l-1,0)
        r=max(r-1,1)
        cnt+=1

main()