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

signed main()
{
    ios::sync_with_stdio(false);
    cin.tie(0);

    int n;
    cin >> n;
    int a = 0, b = 0, d = 0;
    bool f = true;
    while (n > 0)
    {
        if (f)
            a += n % 10;
        else
            b += n % 10;
        n /= 10;
        f = !f;
        d++;
    }
    int ans;
    if (d == 1)
        ans = n;
    else if (a + b == 1)
        ans = 10;
    else
        ans = a + b;
    cout << ans << endl;
}