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<iostream>
#include<algorithm>
#include<vector>
#include<queue>
#include<map>
#include<set>
#include<stack>
using namespace std;
typedef long long ll;
ll MOD = 1e9+7;
#define rep(i,n) for(int i = 0; i < (n); ++i)
int main() {
    int n;
    cin >> n;
    int ans = 1e8;
    for ( int i = 1; i < n; ++i ) {
        int a = i;
        int b = n - i;
        int sum = 0;
        while(1) {
            if ( a == 0 ) break;
            sum += a%10;
            a /= 10;
        }
        while(1) {
            if ( b == 0 ) break;
            sum += b%10;
            b /= 10;
        }
        ans = min(ans, sum);
    }
    cout << ans << endl;
    return 0;
}