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++)

using namespace std;
using ll = long long;
int mod = 1000000007;

void solve();

int main(void){
    int N; cin >> N;
    int l = 1, r = N-1;
    int ans = 1000;
    while(l <= r){
        int val = 0;
        int work1 = l, work2 = r;
        while(work1 > 0){
            val += work1 % 10;
            work1 /= 10;
        }
        while(work2 > 0){
            val += work2 % 10;
            work2 /= 10;
        }
        if(val < ans) ans = val;
        l++; r--;
    }
    cout << ans << endl;
    return 0;
}

void solve(){}