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;
typedef long long ll;
#define rep(i, n) for (int i = 0; i < (int)(n); i++)

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

    int tmp = n;
    bool is_div = false;
    int div = 100000;
    rep(i, 5) {
        if (tmp % div == 0) {
            is_div = true;
            break;
        }
        div /= 10;
    }
    if (is_div) {
        cout << "10" << endl;
        return 0;
    }
    int sum = 0;

    while (tmp != 0) {
        sum += tmp % 10;
        tmp = tmp / 10;
    }
    cout << sum << endl;
    return 0;
}