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 static System.Console;
using static System.Math;
 
public class Hello{
    public static void Main(){
        int kazu = int.Parse(ReadLine());
        int a = 1;
        int b = 0;

        while(a<kazu){
            a*=10;
        }
        a/=10;
        b=kazu-a;
        
        int count = 0;
        while(a>0 || b>0){
            count += a%10 + b%10;
            a/=10;
            b/=10;
//            WriteLine("{0} {1} {2}",count,a,b);
        }
        WriteLine(count);
    }
}