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 Go (1.6) (judge verdict: Accepted)

///
// File:  a.go
// Author: ymiyamoto
//
// Created on Sun Jun  3 21:07:03 2018
//
package main

import (
	"fmt"
	"strconv"
)

var N int

func min(a, b int) int {
	if a < b {
		return a
	}
	return b
}

func main() {
	fmt.Scan(&N)

	v := 1 << 30
	for i := 1; i < N; i++ {
		var val int
		s := strconv.Itoa(i)
		for j := range s {
			val += int(s[j] - '0')
		}
		s = strconv.Itoa(N - i)
		for j := range s {
			val += int(s[j] - '0')
		}
		v = min(v, val)
	}

	fmt.Println(v)
}