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)

def sum_of_dig(n):
    s = str(n)
    l = len(s)
    return sum(int(s[i]) for i in range(l))

N = int(input())
ans = sum_of_dig(N//2)+sum_of_dig(N-N//2)
for A in range(1, N//2):
    tmp = sum_of_dig(A)+sum_of_dig(N-A)
    if ans > tmp:
        ans = tmp
else:
    print(ans)