Regex and Parsing Group, Groups and GroupDict.py

import re
expression=r"([a-zA-Z0-9])\1+"
m=re.search(expression,raw_input())
if m:
    print m.group(1)
else:
    print -1        
    
    
    
'''
group()

A group() expression returns one or more subgroups of the match.
Code

>>> import re
>>> m = re.match(r'(\w+)@(\w+)\.(\w+)','username@hackerrank.com')
>>> m.group(0)       # The entire match 
'username@hackerrank.com'
>>> m.group(1)       # The first parenthesized subgroup.
'username'
>>> m.group(2)       # The second parenthesized subgroup.
'hackerrank'
>>> m.group(3)       # The third parenthesized subgroup.
'com'
>>> m.group(1,2,3)   # Multiple arguments give us a tuple.
('username', 'hackerrank', 'com')

groups()

A groups() expression returns a tuple containing all the subgroups of the match.
Code

>>> import re
>>> m = re.match(r'(\w+)@(\w+)\.(\w+)','username@hackerrank.com')
>>> m.groups()
('username', 'hackerrank', 'com')

groupdict()

A groupdict() expression returns a dictionary containing all the named subgroups of the match, keyed by the subgroup name.
Code

>>> m = re.match(r'(?P<user>\w+)@(?P<website>\w+)\.(?P<extension>\w+)','myname@hackerrank.com')
>>> m.groupdict()
{'website': 'hackerrank', 'user': 'myname', 'extension': 'com'}

'''