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 (GCC 5.4.1) (judge verdict: Accepted)

#include <stdio.h>
#include <stdlib.h>
#include <math.h>

int teste(int n){
    if(n < 10){
        return n;
    }
    else{
        return n%10 + teste(n/10);
    }
}
int main()
{
    int n, menor = 100001, i, aux, resto;
    scanf("%d", &n);
    if(n >= 10){
        for(i = 1; i < n / 2; i++){
            int resto = n - i;
            aux = teste(i) + teste(resto);
            if(aux < menor)
                menor = aux;
        }
        printf("%d\n", menor);
    }
    else
        printf("%d\n", n);
}