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.Linq;//リストの使用
using System.Collections.Generic;
class Program
{
	static void Main()
	{
	long n = long.Parse(Console.ReadLine());//int.Parseは文字列を整数に変換。
  long memo = 0;
  long a = 0;
  long answer = long.MaxValue;

  for(long i = 1; i <= n-1; i++)
  {
    memo = 0;
    memo += i/100000 + (i/10000)%10 + (i/1000)%10 +(i/100)%10 +(i/10)%10 + i%10;
    a = n - i;
    memo += a/100000 + (a/10000)%10 + (a/1000)%10 +(a/100)%10 +(a/10)%10 + a%10;
    answer = Math.Min(answer, memo);
  }
  
	Console.WriteLine(answer);//WriteLineをWriteとすると、改行なしで出力。
	}
}