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 7.10.3) (judge verdict: Accepted)

main = do
  n <- readLn
  s <- getLine
  t <- getLine
  let result = map (\x -> solve (drop x s) t) [0..n]
  out result [n..2*n]

solve :: String -> String -> Bool
solve [] _ = True
solve (s:ss) (t:ts) = if s == t
                        then solve ss ts
                        else False

out :: [Bool] -> [Int] -> IO ()
out (True:bs) (i:is) = print i
out (False:bs) (i:is) = out bs is