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 PHP7 (7.0.15) (judge verdict: Accepted)

<?php
$n = fgets(STDIN, 4096);
for ($a=1; $a<=$n-1 ;$a++)
{
  preg_match_all("([0-9])", $n-$a, $m);
  preg_match_all("([0-9])", $a, $o);
  $array[] = array_sum($o[0]) + array_sum($m[0]);
}
echo min($array);die();