low = 10
high = pow(10, 9)
mid = (low + high) // 2
count = 0
print('?', 40)
if int(input()) == -1:
    count += 1
    for i in range(9, 30):
        print('?', i)
        r = int(input())
        if r == 0:
            print('!', i + count)
            break
        count += 1
else:
    count += 1
    while True:
        print('?', mid)
        r = int(input())
        if r == 0:
            print('!', mid + count)
            break
        if r == 1:
            low = mid - 1
        if r == -1:
            high = mid
            low -= 1
        mid = (low + high) // 2
        count += 1