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;

public class Hello
{
    public static void Main()
    {
        var n = int.Parse(Console.ReadLine().Trim());
        if (n == 2 | n == 3) { Console.WriteLine(n); goto end; }
        var ret = 999999999;
        for (int i = 1; i < n/2; i++)
        {
            var w = getAns(i) + getAns(n - i);
            ret = Math.Min(ret, w);
        }
        Console.WriteLine(ret);
        end:;
    }
    public static int getAns (int aa)
    {
        var a = aa.ToString();
        var ret = 0;
        for (int i = 0; i < a.Length; i++)
            ret += int.Parse(a[i].ToString());
        return ret;
    }
}