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 <bits/stdc++.h>
using namespace std;

int keta(int n) {
    string S = to_string(n);
    int tmp=0;
    for (char c:S) tmp += c - '0';
    return tmp;
}

int main(){
    int N;
    cin >> N;
    int minwa=1000000;
    for (int a=1;a<N;a++) {
        int wa=0;
        wa = keta(a) + keta(N-a);
        if(wa<=minwa)  {
            minwa = wa ;
        }
    }
    cout << minwa << endl;
}