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;

namespace AtCoder.AGC025
{
    class a
    {
        static Dictionary<int, long> fact = new Dictionary<int, long>();

        static void Main(string[] args)
        {
            var line = Console.ReadLine().Trim();
            var cnt = 0;
            for(var i = 0; i < line.Length; ++i)
            {
                cnt += line[i] - '0';
            }
            Console.WriteLine(cnt != 1 ? cnt : 10);
        }
    }
}