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 Lua (5.3.2) (judge verdict: Accepted)

local someTable = {}
for i=1,10 do
    someTable[10^i] = true
end

function suibian(a)
    local total = 0
    if someTable[a] then
        print(10)
        return
    end
    a = tostring(a)
    for i=1,string.len(a) do
        total = tonumber(string.sub(a,i,i))+total
    end
    print(total)
end
local n = io.read("*n")
suibian(n)