l = 0
r = 100
mid = t = 0
while l != r - 1:
    mid = (l + r) // 2
    dbg(f"〇l:{l}, r:{r}, mid:{mid}")
    print('?', mid)
    t = int(input())
    dbg(f"▼t:{t}")
    if t == 1:
        l = mid
    else:
        r = mid
print('!', l)