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)

object Main {
  def main(args: Array[String]): Unit = {
    val Array( standard_num, nums ) = io.StdIn.readLine.split(" ").map{_.toInt}

    if( nums == 0 ) println( standard_num )
    else {
      val illegal_nums = io.StdIn.readLine.split(" ").map{_.toInt}
      val check_nums = ( -2000 to 2000 ).filter( !illegal_nums.contains( _ ) )
      var answer_num = 100000
      var min_value  = 100000

      check_nums.foreach{ i =>
        val check_value = Math.abs( standard_num - i )
        if( check_value < min_value ) {
          min_value = check_value
          answer_num = i
        }
      }

      println( answer_num )
    }
  }
}