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 PHP7 (7.0.15) (judge verdict: Accepted)

<?php
/*
    http://agc006.contest.atcoder.jp/tasks/agc006_a
 
    Score  :
    Result :
    Time   : ms
    Memory : KB
 */
 
// define('DEBUG', true);
define('DEBUG', false);
 
fscanf(STDIN, "%d", $N);
fscanf(STDIN, "%s", $s);
fscanf(STDIN, "%s", $t);
 
for ($i = $N; $i >= 0; $i--) {
	$ss = substr($s, strlen($s) - $i);
	$tt = substr($t, 0, $i);
	// echo "{$ss} {$tt}\n";
	if ($ss == $tt) {
		echo ($N * 2 - $i) . PHP_EOL;
		exit;
	}
}