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 Ruby (2.3.3) (judge verdict: Accepted)

# encoding: ISO-8859-1
$n = gets.to_i
$s = gets.chop
$t = gets.chop

def st_intersection?(i)
  $s[-i..-1] ==  $t[0..(i-1)]
end

def find_largest_intersection
  $n.downto(1) do |i|
    return i if st_intersection? i
  end
   return 0
end


common = find_largest_intersection


puts 2 * $n - common