=====Function Descriptions=====
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'}
=====Problem Statement=====
You are given a string S.
Your task is to find the first occurrence of an alphanumeric character in (read from left to right) that has consecutive repetitions. 
=====Input Format=====
A single line of input containing the string S.
=====Constraints=====
0<len(S)<100
=====Output Format=====
Print the first occurrence of the repeating character. If there are no repeating characters, print -1.
import re
s = input()
res = re.search(r'([A-Za-z0-9])\1',s)
if res == None:
    print((-1))
else:
    print((res.group(1)))

import re
s = input()
res = re.search(r'([A-Za-z0-9])\1',s)
if res == None:
    print((-1))
else:
    print((res.group(1)))
