print("? 99", flush=True)
S = input()
count = 0

if S == "0":
    print("! 99", flush=True)
elif S == "-1":
    while 1:
        print("? 0", flush=True)
        S = input()
        count += 1
        if S == "0":
            print("!", count, flush=True)
            break
else:
    L = 99
    R = int(1e9) + 1
    while 1:
        mid = (L + R) // 2
        print("?", mid - 1 - count, flush=True)
        S = input()
        if S == "0":
            print("!", mid, flush=True)
            break
        elif S == "-1":
            R = mid
        else:
            L = mid
        count += 1