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 (2.7.1) (judge verdict: Accepted)

class Problem
  attr_accessor :a, :b, :n, :m, :h, :w, :x, :y, :s ,:t, :k

  def initialize
    @n = gets.to_s.to_i
  end

  def solve
    ans = 1000
    1.upto(n-1) do |a|
      b = n - a
      cnt = calc(a,b)
      ans = cnt if cnt < ans
    end
    ans
  end

  def calc(a,b)
    a.digits.sum + b.digits.sum
  end

  def show(ans)
    puts ans
  end
end

Problem.new.instance_eval do
  show(solve)
end