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))