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 PHP (5.6.30) (judge verdict: Accepted)

<?php

    function sum_calc($target) {
        $sum = 0;
        $target_len = strlen($target);
        for ($i = 0; $i < $target_len; $i++) {
            $sum = $sum + substr($target, ($target_len - $i - 1), 1);
        }
        return $sum;
    }

    fscanf(STDIN, "%d", $stdin);
    $min = 100000;
    for ($a = 1; $a <= $stdin / 2; $a++) {
        $b = $stdin - $a;
        $sum_a_b = sum_calc($a) + sum_calc($b);
        if ($sum_a_b < $min) $min = $sum_a_b;
    }
    echo($min);

?>