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: Runtime Error)

import java.util.*
import java.math.*
import java.lang.Math.*

val readString: ()->String = {readLine()!!}
val readInt: ()->Int = {readLine()!!.toInt()}
val readLong: ()->Long = {readLine()!!.toLong()}
val readIntArray: ()->IntArray = {readLine()!!.split(' ').map{it.toInt()}.toIntArray()}
val readLongArray: ()->LongArray = {readLine()!!.split(' ').map{it.toLong()}.toLongArray()}
val errPrintln: (String)->Unit = {msg -> System.err.println(msg)}
val MOD = 1_000_000_007L
val INF = Int.MAX_VALUE/2
val LINF = Long.MAX_VALUE/2


fun solve(X: Int, P: IntArray): Int {
    var cand = ArrayList<Int>()
    for (i in 0..101) {
        if (P.contains(i)) continue
        else cand.add(i)
    }

    var res = 0
    var dist = INF
    for (c in cand) {
        if (dist > abs(c - X)) {
            dist = abs(c-X)
            res = c
        }
    }

    return res
}


fun main(args: Array<String>){
    val (X,N) = readIntArray()
    val P = readIntArray()

    val ans = solve(X, P)

    println(ans)
}