numMin=10
numMax=1000000001
turn=0
while True:
	chkNum=100 if turn==0 else int((numMin+numMax)/2);
	print("? {0}".format(chkNum),flush=True)
	chk=input()
	if chk=="1": numMin=chkNum
	elif chk=="-1": numMax=chkNum
	else:
		print(f"! {chkNum+turn}",flush=True)
		break
	if 0<numMin: numMin-=1
	numMax-=1
	turn+=1