def digit_sum(n):
	s = 0
	while n > 0:
		s += n % 10
		n /= 10
	return s

max_sum = 0

for i in range(2, 100):
	for j in range(2, 100):
		s = digit_sum(i**j)
		if s > max_sum:
			max_sum = s

print max_sum