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 Kotlin (1.3.71) (judge verdict: Accepted)

import java.io.PrintWriter
import kotlin.math.pow

fun next() = readLine()!!
fun nextInt() = next().toInt()
fun nextLong() = next().toLong()
fun nextDouble() = next().toDouble()
fun nextList() = next().split(" ")
fun nextIntList() = nextList().map(String::toInt)
fun nextLongList() = nextList().map(String::toLong)
fun nextDoubleList() = nextList().map(String::toDouble)

val pw = PrintWriter(System.out)
fun print(s: Any = "") = pw.print(s)
fun println(s: Any = "") = pw.println(s)

fun <T> Iterable<T>.join(separator: CharSequence = ", ", prefix: CharSequence = "", postfix: CharSequence = "") = joinToString(separator, prefix, postfix)
fun <T> Array<T>.join(separator: CharSequence = ", ", prefix: CharSequence = "", postfix: CharSequence = "") = joinToString(separator, prefix, postfix)
fun Int.pow(n: Int) = pow(n.toLong())
fun Int.pow(n: Long) = toDouble().pow(n.toDouble()).toLong()
fun Long.pow(n: Int) = pow(n.toLong())
fun Long.pow(n: Long) = toDouble().pow(n.toDouble()).toLong()

fun main(args: Array<String>) {
    main()
    pw.flush()
}

fun main() {
    val N = nextInt()
    val S = next()
    val T = next()
    for (n in N downTo 1) {
        if (S.takeLast(n) == T.take(n)) {
            println(2 * N - n)
            return
        }
    }
    println(2 * N)
}