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: Wrong Answer)

#include<iostream>
using namespace std;

int sumOfDigits(int n) {
  int sum = 0;
  while (n / 10 != 0) {
    sum += n % 10;
    n /= 10;
  }
  sum += n;
}

int main() {
  int N; cin >> N;
  int min = 90;
  for (int i = 1; i < N; i++) {
    int sum = sumOfDigits(i) + sumOfDigits(N - i);
    if (sum < min) min = sum;
  }
  cout << min << endl;
}