import re  
pattern = '[1-9]?\d$|100$'
v = re.match(pattern,'0')
print(v)
v = re.match(pattern,'10')
print(v)
v = re.match(pattern,'100')
print(v)
v = re.match(pattern,'99')
print(v)
v = re.match(pattern,'200')
print(v)
