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 System.Collections.Generic;
using System.Linq;
//全て投げ出して全探索してもいいんじゃない？ used to be O(N log N)?でeasy
namespace AtCoderTemplate
{
    public class App
    {
        public static void Main(string[] args)
        {
            var k = int.Parse(Console.ReadLine()); Console.WriteLine(Enumerable.Range(1,k/2).Select(v=>new {p=v,q=k-v}).Select(v=>v.p.ToString().ToCharArray().Sum(c=>c-'0')+v.q.ToString().ToCharArray().Sum(c=>c-'0')).Min());
        }
    }
}