题解 | #合法IP#

while True: try: s = input().split('.') result = 'YES' if len(s) != 4: print('NO') else: for i in s:
if not i.isdigit() or (i.startswith('0') and len(i) > 1): result = 'NO' continue

            if i.startswith('+'):
                result = 'NO'
                continue
            
            if int(i) < 0 or int(i) > 255: 
                result = 'NO'
                continue
            
        print(result)
    
except:
    break