Problem:
Score : 200 points

Problem Statement

Snuke is interested in strings that satisfy the following conditions:

The length of the string is at least N.

The first N characters equal to the string s.

The last N characters equal to the string t.

Find the length of the shortest string that satisfies the conditions.

Constraints

1≤N≤100

The lengths of s and t are both N.

s and t consist of lowercase English letters.

Input

The input is given from Standard Input in the following format:

N
s
t

Output

Print the length of the shortest string that satisfies the conditions.

Sample Input 1

3
abc
cde

Sample Output 1

5

The shortest string is abcde.

Sample Input 2

1
a
z

Sample Output 2

2

The shortest string is az.

Sample Input 3

4
expr
expr

Sample Output 3

4

The shortest string is expr.

Solution in Haskell (GHC 8.8.3) (judge verdict: Accepted)

import qualified Data.ByteString.Char8 as BS
import Data.Maybe

readInt = fst . fromJust . BS.readInt
readIntList = map readInt . BS.words
readString = map BS.unpack . BS.words

getInt = readInt <$> BS.getLine
getString = readString <$> BS.getLine

simulate as bs k n
  | as' == bs' = 2 * n - k
  | otherwise = simulate as bs (k -1) n
  where
    as' = drop (n - k) as
    bs' = take k bs

main = do
  n <- getInt
  [s] <- getString
  [t] <- getString
  print $ simulate s t n n