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 = trim(fgets(STDIN));
	$f = true;
	if($n[0] != '1') $f = false;
	for($i=1; $i<strlen($n); $i++){
	    if($n[$i] != '0') $f = false;
	}
	if($f) echo 10;
	else{
	    $ans = 0;
	    for($i=0; $i<strlen($n); $i++){
	        $ans += (int)$n[$i];
	    }
	    echo $ans;
	}
?>