import sys

l = 0
r = 10 ** 9 + 1
n = 140
while r - l > 1:
    pos = (r + l) // 2
    print ("? " + str(pos), end="\n")
    sys.stdout.flush()
    flg = int(input())

    if flg:
        r = pos
    else:
        l = pos
print("! " + str(r), end="\n")
sys.stdout.flush()