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)

// Don't Lose Hope, Nor Be Sad 

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

  #define lp(start,finish) for(int i=start; i<finish; i++)
  #define read freopen("input.txt","r",stdin);
  #define fast ios_base::sync_with_stdio(0),cin.tie(0),cout.tie(0);

int main(){
	//read
	int a,sum=0;
	cin >> a;
	if(a%10==0)cout<<"10\n";
	else
	{	while(a){
		sum+= a%10;
		a/=10;
		}
		cout << sum << endl;
	}
	return 0;
}