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 java.util.Scanner

fun main(args: Array<String>) {
  val cin = Scanner(System.`in`)
  val x = cin.nextInt()
  val n = cin.nextInt()
  val s = Array<Boolean>(105, {true})

  for (i in 0 until n) {
    val a = cin.nextInt()
    s[a] = false
  }

  for (i in 0..100) {
    if (x - i >= 0) {
      if (s[x - i]) {
        println(x - i)
        cin.close()
        return
      }
    }
    if (x + i <= 100) {
      if (s[x + i]) {
        println(x + i)
        cin.close()
        return
      }
    }
  }

  cin.close()
}