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 C# (Mono 4.6.2.0) (judge verdict: Wrong Answer)

using System;

class Program {
    static void Main(string[] args) {
        int d = int.Parse(Console.ReadLine()), i;
        var a = Console.ReadLine();
        var b = Console.ReadLine();
        string c = null;
        for (i = 0; i < a.Length; i++) {
            if (a[a.Length - i - 1] == b[i]) {
                c += b[i];
            } else {
                break;
            }
        }
        Console.WriteLine(i != 0 ? a.Substring(0, i) + c + b.Substring(i) : a + b);
    }
}