def average(a, b):
    n = max(len(a), len(b))
a = debase(pad(a, n))
b = debase(pad(b, n))
return enbase((a + b) / 2)
print(average('a', 'z'))
print(average('aa', 'zz'))
print(average('aa', 'az'))
print(average('cat', 'doggie'))
print(average('google', 'microsoft'))
print(average('microsoft', 'google'))
Average of two strings in alphabetical/lexicographical order