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, b = 1, N-1
while a <= b:
  sum_d_a = sum(map(int, str(a)))
  sum_d_b = sum(map(int, str(b)))
  ans = min(ans, sum_d_a + sum_d_b)
  a += 1
  b -= 1

print(ans)