import sys
def request(s):
	print s
	sys.stdout.flush()
	return raw_input()
l=1
h=int(10**9)
while h-l>1:
	m=(l+h)/2
	r=request("? "+`m`)
	if r=="0":
		h=m-1
	else:
		l=m
	#print l,h
r=request("? "+`h`)
if r=="1":
	print"! "+`h`
else:
	print"! "+`l`
sys.stdout.flush()