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: Runtime Error)

n,*z=`dd`.split.map &:to_i;t=*0...n;*e=t;a=z.shift n+1;n.downto(1){|i|a[i]-=a[i-1]};k,*z=z;z.map{|x|t[x-2,2]=t[x-1],t[x-2]};60.times{|i|k[i]>0&&e.map!{|q|t[q]};t=t.map{|q|t[q]}};k,*a=a;e.map{|q|p k;k+=a[q]}