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++14 (GCC 5.4.1) (judge verdict: Accepted)

#include <iostream>
using namespace std;

int findSumOfDigits(int x) {
  int sum = 0;
  while (x > 0) {
    sum += x % 10;
    x /= 10;
  }
  return sum;
}

int main () {
  int n;
  cin >> n;

  int min_sum = 1000000;
  for (int a = 1; a <= n -1; a++) {
    min_sum = min(min_sum, findSumOfDigits(a) + findSumOfDigits(n-a));
  }
  cout << min_sum << endl;
}