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)

n = gets.to_i
if n == 100 || n == 1000 || n == 10000 || n == 100000 || 1000000 then
  r = 10
else
  b = n - 1
  c = b.to_s.split("").map(&:to_i)
  r = 0
  c.each do |i|
    r += i
  end
  r = r + 1
end
print("#{r}\n")