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())
n = list(str(N))
sumN = sum(map(int,n))
lenN = len(n)
lengN = 10 ** (lenN - 1)

if sumN == 1:
    print(10)
elif lenN == 1:
    print(n[0])
else:
    A = N // lengN
    B = sum(map(int,list(str(N % lengN))))
    print(A + B)