def same(x,y): return ('.', '.') if x==y else (x,y)
a = "atcgatcgaaa"
b = "atccagcgaac"
c = [ same(x,y) for x,y in zip(a,b) ]
c1, c2 = zip(*c)
print(''.join(c1))
print(''.join(c2))
ZGVmIHNhbWUoeCx5KTogcmV0dXJuICgnLicsICcuJykgaWYgeD09eSBlbHNlICh4LHkpCgphID0gImF0Y2dhdGNnYWFhIgpiID0gImF0Y2NhZ2NnYWFjIgpjID0gWyBzYW1lKHgseSkgZm9yIHgseSBpbiB6aXAoYSxiKSBdCmMxLCBjMiA9IHppcCgqYykKCnByaW50KCcnLmpvaW4oYzEpKQpwcmludCgnJy5qb2luKGMyKSk=