def ask(x):
    print("?", x, flush=True)
    return int(input())


x = ask(98)
if x == 0:
    print("!", 98, flush=True)
elif x == -1:
    for i in range(1, 99):
        if ask(0) == 0:
            print("!", i, flush=True)
            break
else:
    l = 0
    r = 1 << 30
    t = 1
    while r - l > 1:
        mid = (l + r) // 2
        if ask(mid - t) >= 0:
            r = mid
        else:
            l = mid
        t += 1
    print("!", r, flush=True)