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 Perl (v5.18.2) (judge verdict: Accepted)

chomp( my $n = <> );
chomp( my $s = <> );
chomp( my $t = <> );

while ( $s ) {
    $s eq $t and print 2*$n - length $s and exit;
    substr $s, 0, 1, '';
    substr $t, -1, 1, '';
}
print 2*$n;