import sys import os ip_string = sys.stdin.readline().strip().split(".") result = "YES" if len(ip_string) != 4: result = "NO" try: for i in ip_string: if "+" in i: result = "NO" if int(i) >255 or int(i) < 0: result = "NO" if len(i) > 1 and i.startswith("0"): result = "NO" except: result = "NO" print(result)