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: Wrong Answer)

import kotlin.math.abs

fun main() {
    val line = readLine()!!.split(" ").map { it.toInt() }
    val x = line[0]
    val n = line[1]
    val pList = if (n > 0) {
        readLine()!!.split(" ").map { it.toInt() }
    } else {
        readLine()
        listOf()
    }

    if (n == 0) {
        print(x)
        return
    }

    var i = x - 1
    while (true) {
        if (pList.contains(i)) {
            i -= 1
        } else {
            break
        }
    }

    var j = x + 1
    while (true) {
        if (pList.contains(j)) {
            j += 1
        } else {
            break
        }
    }

    val result = if (abs(x - i) > abs(j - x)) {
        j
    } else if (abs(x - i) == abs(j - x)) {
        i
    } else {
        i
    }
    print(result)

}