Problem:
Score : 300 points

Problem Statement

Given are an integer X and an integer sequence of length N: p_1, \ldots, p_N.

Among the integers not contained in the sequence p_1, \ldots, p_N (not necessarily positive), find the integer nearest to X, that is, find the integer whose absolute difference with X is the minimum. If there are multiple such integers, report the smallest such integer.

Constraints

1 \leq X \leq 100

0 \leq N \leq 100

1 \leq p_i \leq 100

p_1, \ldots, p_N are all distinct.

All values in input are integers.

Input

Input is given from Standard Input in the following format:

X N
p_1 ... p_N

Output

Print the answer.

Sample Input 1

6 5
4 7 10 6 5

Sample Output 1

8

Among the integers not contained in the sequence 4, 7, 10, 6, 5, the one nearest to 6 is 8.

Sample Input 2

10 5
4 7 10 6 5

Sample Output 2

9

Among the integers not contained in the sequence 4, 7, 10, 6, 5, the ones nearest to 10 are 9 and 11. We should print the smaller one, 9.

Sample Input 3

100 0

Sample Output 3

100

When N = 0, the second line in the input will be empty. Also, as seen here, X itself can be the answer.

Solution in Kotlin (1.3.71) (judge verdict: Accepted)

fun main(args: Array<String>) {
    var (x, n) = readLine()!!.split(" ").map { it.toInt() }
    val planePInput = readLine()
    val pList = if (planePInput.isNullOrEmpty()) {
        null
    } else {
        planePInput.split(" ").map { it.toInt() }
    }

    var distance = 0
    val forbiddenList: ArrayList<Int>
    if (pList == null) {
        println(x)
    } else {
        forbiddenList = pList as ArrayList<Int>
        while (true) {
            if (forbiddenList.contains(x - distance)) {
                if (forbiddenList.contains(x + distance)) {
                    distance++
                    continue
                } else {
                    println(x + distance)
                    break
                }
            } else {
                println(x - distance)
                break
            }
        }
    }
}