A bitstring (str) is pattern that only consists of zeroes (0) and ones (0).

Write a function bitmask that takes two string (str) arguments: a string s (str) and a bitstring m. The function must return the string (str) obtained by encoding s using the bitwise exclusive or (xor) with mask m.

Example

>>> bitmask('Hello, world!', '00101010')
'bOFFE\x06\n]EXFN\\x0b'
>>> bitmask('bOFFE\x06\\n]EXFN\x0b', '00101010')
'Hello, world!'