ip = input("Please enter an IP address: ")
ip = ip.split(":")

for i in range(len(ip)):
	ip[i] = int(ip[i], 16)

if len(ip) != 8:
	print("It is not a valid IPv6 address.")
	quit()
else:
	pass

for i in ip:
	if len(str(i)) > 5:
		print("It is not a valid IPv6 address.")
		quit()
	else:
		pass

for i in ip:
	if int(i) > 65535:
		print("It is not a valid IPv6 address.")
		exit()
else:
	print("It is a valid IPv6 address.")