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)

n = int(input())

def sum1(a):
    num = 0
    sn = str(a)
    for i in range(len(sn)):
        num += int(sn[i])
    return num
ans = 10**10
for i in range(1,n+1):
    ans = min(ans,sum1(i)+sum1(n-i))
    #print(ans,i,n-i)#,sum1(i),sum1(n-i))
print(ans)