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 Scala (2.13.1) (judge verdict: Accepted)

import scala.io.StdIn._

object Main extends App {
  val Array(x, n) = readLine.split(" ").map(_.toInt)

  if (n > 0) {
    val p = readLine.stripMargin.split(" ").map(_.toInt).toSet

    val up = (x to 101).find(!p.contains(_)).get
    val down = (x - 1 to 0 by -1).find(!p.contains(_)).get

    val upDiff = up - x
    val downDiff = x - down

    val ans = if (downDiff <= upDiff) down else up

    println(ans)
  } else {
    println(x)
  }
}