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;
class Program
{
	static void Main(string[] args)
	{
		string str = Console.ReadLine();
		int N = int.Parse(str);
		int min = 999999;
		for(var i=1;i<=N/2;i++){
			int count = 0;
			count += i/100000;
			count += (i/10000) % 10;
			count += (i/1000) % 10;
			count += (i/100) % 10;
			count += (i/10) % 10;
			count += i%10;
			int j = N-i;
			count += j/100000;
			count += (j/10000) % 10;
			count += (j/1000) % 10;
			count += (j/100) % 10;
			count += (j/10) % 10;
			count += j%10;
			min = Math.Min(min,count);
		}
		Console.WriteLine(min);
	}
}