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;

//AとBの和が25

//各位の和
int func(int x){
    if(x/10 == 0) return x;
    return func(x/10) + x%10;
}

int N;
int main()
{
    cin>>N;
    int mi= 1000000000;
    for (int A = 1; A <=(int)(N/2) ; A++)
    {
        int B = N-A;
        // cout << "A:" << A << endl;
        // cout << "B:" << B << endl;

        mi = min(mi, func(A) + func(B));
    }
    
    cout << mi << endl;
        
    return 0;
}