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 OCaml (4.02.3) (judge verdict: Accepted)

let n = read_int ()
let s = read_line ()
let t = read_line ()
let f m = Printf.printf "%d\n" @@ 2 * n - m; exit 0
let _ = for i = 0 to n - 1 do if String.(sub s i (n - i) = sub t 0 (n - i)) then f (n - i) done; f 0