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 Python (3.4.3) (judge verdict: Wrong Answer)

# https://atcoder.jp/contests/agc025/tasks/agc025_a

import itertools
import collections
import bisect

def main():
    N = int(input())
    ans = 10**5
    for i in range(2, N):
        j = N - i
        ans = min(ans, sum(map(int, list(str(i)))) + sum(map(int, list(str(j)))))
    print(ans)


if __name__ == '__main__':
    main()