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 Kotlin (1.0.0) (judge verdict: Accepted)

fun main(args: Array<String>) {
    val n = readLine()?.toInt() ?: return
    var minSum = Int.MAX_VALUE
    for (a in 1 until n) {
        val b = n - a
        val sum = sum(a) + sum(b)
        if (sum < minSum) {
            minSum = sum
        }
    }
    println(minSum)
}

private fun sum(n: Int): Int {
    var sum = 0
    var v = n
    while (v > 0) {
        sum += v % 10
        v /= 10
    }
    return sum
}