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>

#define rep(i,n) for(int i = 0; i < (n); i++)
#define ll long long

using namespace std;

int main(){
  int n;cin>>n;
  int result=n;
  rep(i,n-1){
    int t = 0;
    int a=i+1,b=n-i-1;
    int ta,tb;
    rep(i,6){
      ta = a%10;
      t+=ta;
      a/=10;
      tb = b%10;
      t+=tb;
      b/=10;
    }
//if(t<result)cout<<t<<endl;
    result = min(result, t);
  }

  cout<<result;
  return 0;
}