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>
long int digitos(long int n){
    long int x,y;

    x = n%10; 
    int r = 0;

    y = (n - x)/10;
    if(n/10==1000){
        return 10;
    }else{
        return 1;
    }
    

    if (y < 1){
          return x;
          }
    else {
          return x + digitos(y); 
         }
    }
int main(){
    long int somado;

    scanf ("%li",&somado);
    printf ("%li\n",digitos(somado));

}