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 Java8 (OpenJDK 1.8.0) (judge verdict: Accepted)

import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long n = sc.nextLong();
		long ans = Long.MAX_VALUE;
		for(int i = 1 ; i * 2 <= n ; i++) {
			long j = n - i;
			long a = func(i);
			long b = func(j);
			ans = Math.min(a + b, ans);

		}
		System.out.println(ans);
	}

	static long func(long x) {
		long ret = 0;
		while(x > 0) {
			ret += x % 10;
			x /= 10;
		}
		return ret;
	}

}