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 9.2.1) (judge verdict: Wrong Answer)

#include <stdio.h>

int main(void){
  int n, i, a, b;
  int sum, dig, sum_a, sum_b, result= 10000000000;

  scanf("%d", &n);
  for(i=2; i<=(n/2+1); i++){
    a = i;
    b = n - i;
    if(b>1){
      sum = 0;
      while(a){
        dig = a % 10;
        sum += dig;
        a = a / 10;
      }
      sum_a = sum;
      sum = 0;
      while(b){
        dig = b % 10;
        sum += dig;
        b = b / 10;
      }
      sum_b = sum;
      if(result>(sum_a+sum_b))  result = sum_a + sum_b;
    }
  }

  printf("%d\n", result);

  return (0);
}