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 Scala (2.11.7) (judge verdict: Runtime Error)

object Main {
  def main() = {
    val N = readLine.toInt
    val ss = readLine.toString
    val tt = readLine.toString

    def loop(s: String)(t: String): Int = {
      if (s == "") {
        if (t == "")
          ss.length + tt.length
        else
          loop(ss)(t.take(t.length-1))
      } else if (s == t)
        (ss.length - s.length) + tt.length - t.length + 1
      else loop(s.tail)(t)
    }
    if (ss == tt)
      println(ss.length)
    else
      println(loop(ss)(tt))
  }
}