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 main() {
	int N;
	cin >> N;
	int rr = 1<<30;
	for (int i = 1; i < N; ++ i) {
		int a = i;
		int b = N - i;
		int r = 0;
		while (a > 0) { r += a % 10; a /= 10; }
		while (b > 0) { r += b % 10; b /= 10; }
		rr = min(rr, r);
	}
	cout << rr << endl;
}