Problem:
Score : 200 points

Problem Statement

Takahashi has two positive integers A and B.

It is known that A plus B equals N.
Find the minimum possible value of "the sum of the digits of A" plus "the sum of the digits of B" (in base 10).

Constraints

2 ≤ N ≤ 10^5

N is an integer.

Input

Input is given from Standard Input in the following format:

N

Output

Print the minimum possible value of "the sum of the digits of A" plus "the sum of the digits of B".

Sample Input 1

15

Sample Output 1

6

When A=2 and B=13, the sums of their digits are 2 and 4, which minimizes the value in question.

Sample Input 2

100000

Sample Output 2

10

Solution in Ruby (2.3.3) (judge verdict: Wrong Answer)

#標準入力
n = gets.to_i
answer = []

n.times do |i|
	a = n - i
	b = i

	sum_a = a.to_s.split('').map(&:to_i).inject(:+)
	sum_b = b.to_s.split('').map(&:to_i).inject(:+)

	answer << (sum_a + sum_b)
end
puts answer.min


#よく分からなくなってきた
=begin
n = gets.to_i
count = 0
answer = []

n.times do |i|
	sum = i.to_s.split('').map(&:to_i)

	sum << count
	count += 1

	sum = sum.inject(:+)
	answer << sum
	sum.clear

end
puts answer.min
=end