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: Wrong Answer)

<?php

class Scanner
{
    private $arr = [];
    private $count = 0;
    private $pointer = 0;

    public function next()
    {
        if ($this->pointer >= $this->count) {
            $str = trim(fgets(STDIN));
            $this->arr = explode(" ", $str);
            $this->count = count($this->arr);
            $this->pointer = 0;
        }
        $result = $this->arr[$this->pointer];
        $this->pointer++;
        return $result;
    }

    public function hasNext()
    {
        return $this->pointer < $this->count;
    }

    public function nextInt()
    {
        return (int)$this->next();
    }

    public function nextDouble()
    {
        return (double)$this->next();
    }
}

class out
{
    public static function printIn($str = "")
    {
        echo $str . PHP_EOL;
    }
}

$sc = new Scanner;

$N = $sc->nextInt();
$ans = 1000000;
for ($A = 2; $A <= $N -2 ; $A++) {
  $B = $N - $A;
  $a = array_sum(str_split($A));
  $b = array_sum(str_split($B));
    if ($a + $b < $ans) {
        $ans = $a + $b;
    }
}

echo $ans;