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: Time Limit Exceeded)

fun main(args: Array<String>) {

    val num = readLine()!!.toInt()
    var minNum = Int.MAX_VALUE

    // LOOK 正の整数は1以上
    for (i in 1..num)
        for (j in 1..num)
            if (i + j == num) {
                val iSum = devideUnit(i)
                val jSum = devideUnit(j)

                if (iSum + jSum < minNum)
                    minNum = iSum + jSum
            }

    println(minNum)
}

fun devideUnit(n: Int): Int {

    var loopTarget = n
    var sum = 0

    while (loopTarget > 0) {
        sum += loopTarget % 10
        loopTarget /= 10
    }

    return sum
}