import sys
def ask(Y):
	print "? %d" % Y
	sys.stdout.flush()
	return int(raw_input())

def ans(Y):
	print "! %d" % Y
X = 73507939
B = 100
print X
res = ask(B)
if res == 0:
	ans(B)
elif res < 0:
	for i in range(1,B):
		if ask(0) == 0:
			ans(i)
			break
else:
	left = B
	right = 10**9 + 1
	for i in range(1,B):
		print X - i
		mid = (left + right) / 2
		res = ask(mid-i)
		if res == 0:
			ans(mid)
			break
		elif res == -1:
			right = mid
		else:
			left = mid