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: Wrong Answer)

#include <stdio.h>

int soma(num){
  int soma = 0;

  while (num != 0) {
    soma   += num % 10;
    num  = num / 10;
  }

  return soma;
}

int main(void) {
  int n, a, b, menor;

  scanf("%d", &n);
  a = 1;
  b = n-1;
  menor = n-1;

  while (a < b){
    int somaTemp = soma(a) + soma(b);
    if( somaTemp < menor){
      menor = somaTemp;
    }

    a++;
    b--;
  }

  printf("%d", menor);


  return 0;
}