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: Wrong Answer)

#include <iostream>
using namespace std;
int f(int x){
    int p=0;
    while(x){
        p+=x%10;
        x/=10;
    }
    return p;
}
int main(void){
    int n;
    cin>>n;
    int ans=1e9;
    for(int i=1;i<n/2;i++){
        ans=min(ans,f(i)+f(n-i));
    }
    
    cout<<ans<<endl;
}