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: Accepted)

N = int(input())

ans = float("inf")

A = 0
B = N
for i in range(N//2):

    A += 1
    B -= 1

    if A + B > N:
        break

    else:

        s_a = str(A)
        s_b = list(str(B))

        a = [int(i) for i in s_a]
        b = [int(i) for i in s_b]

        ans = min(ans, sum(a)+sum(b))

print(ans)