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>
using namespace std;

int N;

int digit(int n){
	int ans = 0;
	while(n!=0){
		ans += n%10;
		n /= 10;
	}
	return ans;
}

int main(){
	cin >> N;
	int ans = 1e9;
	for(int i=1;i<=N-1;i++){
		ans = min(ans,digit(i) + digit(N-i));
	}
	cout << ans << endl;
}