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>
#define min(a,b) ((a>b)?b:a)

int sum(int x){
    int i;
    int d_sum = 0;
    for(i=0;i<=6;i++){
        d_sum += x % 10;
        x /= 10;
    }
    return d_sum;
}

int main()
{
    int n;
    scanf("%d", &n);
    int i;
    int min = 1000000;
    for(i=1;i<=n-1;i++){
        min = min(sum(i)+sum(n-i), min);
    }
    printf("%d", min);

    return 0;
}