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 (Clang 3.8.0) (judge verdict: Accepted)

#include <stdio.h>
int main(void){
    int n;
    int a, aa,  b, cou, min=1000000;
    scanf("%d", &n);
    
    for(a=1; a<n; a++){
        cou = 0;
        b = n-a;
        aa = a;
        while(aa > 0){
            cou += aa%10;
            aa /= 10;
        }
        while(b > 0){
            cou += b%10;
            b /= 10;
        }
        
        if(min > cou){
            min = cou;
        }
    }
    printf("%d\n", min);
    
    return 0;
}