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++ (GCC 9.2.1) (judge verdict: Accepted)

#include <bits/stdc++.h>
#define rep(i, n) for (int i = 0; i < (n); ++i)
#define zero_pad(num) setfill('0') << std::right << setw(num)
using namespace std;
using ll = long long;
using ld = long double;
using P = pair<int, int>;

int main() {
    int n;
    cin >> n;
    int ans = 1001001;
    for(int i = 1; i <= n/2; i++){
        int a = n - i;
        int b = i;
        int cnt = 0;
        rep(i, 6){
            cnt += a % 10;
            cnt += b % 10;
            a /= 10;
            b /= 10;
        }
        ans = min(ans, cnt);
    } 
    cout << ans << endl;
}