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>
#include <stdlib.h>
#include <string.h>
#include <math.h>
int main(void){
  int i,j;
  int n;
  int a,b;
  int mina,minb,min;
  int sum;
  scanf("%d",&n);
  min=n;
  for(i=0;i<n/2;i++){
    sum=0;
    a=i+1;b=n-i-1;
    while(a!=0){
      sum += a%10;
      a /= 10;
    }
    while(b!=0){
      sum+=b%10;
      b/=10;
    }
    if(min>sum){
      min=sum;
    }
  }
  printf("%d\n",min);
  return 0;
}