You can do this with the string.find() method in Python. It returns the index of a substring (in this case a character). If the character isn't found it returns -1.
>>> 'nobody'.find('n')
0
>>> 'nobody'.find('N')
-1
You'll need to create a substring of the input line to begin with. You can do this with slicing, e.g.
>>> s='n Monday'
>>> s[2:]
'Monday'
>>> s[0:1]
'n'