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 <iostream>
#include <string>
#include <vector>
#include <cmath>
#include <queue>
#include <map>
#include <set>
#include <stack>
#include<algorithm>
#include<sstream>
#include<iomanip>
#include<deque>
#include<list>


using namespace std;

typedef long long ll;

typedef pair<int, int> pii;

const ll MOD_CONST = 1000000007;
const ll BIG_NUM = 1000000000000000000;
const int BIG_INT = 1000000000;


int sumDig(int num) {
	int sum = 0;
	while (num > 0) {
		sum += num % 10;
		num /= 10;
	}

	return sum;
}

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

	int ans = n;
	for (int a = 1;a < n;a++) {
		int b = n - a;

		ans = min(sumDig(a) + sumDig(b), ans);
	}

	cout << ans << endl;
}