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 C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using static System.Console;
using static System.Math;

public class Hello{
    public static void Main(){
//        string[] input = ReadLine().Split(' ');
        int kazu = int.Parse(ReadLine());
//        int max = int.Parse(input[1]);
        int min = 99999;
        
        for(int i=1;i<=kazu/2;i++){
            int wa = 0;
            //A
            int a = i;
            while(a>0){
                wa += a%10;
                a /= 10;
            }
            //B
            int b = kazu-i;
            while(b>0){
                wa += b%10;
                b /= 10;
            }
            min = Min(min,wa);
        }
        WriteLine(min);
    }
}