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 Java (OpenJDK 11.0.6) (judge verdict: Wrong Answer)

import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class Main {

  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);

    int x = sc.nextInt();
    int n = sc.nextInt();

    if (n == 0) {
      System.out.println(x);
      return;
    }

    List<Integer> ps = new ArrayList<>();
    for (int i = 0; i < n; i++) {
      ps.add(sc.nextInt());
    }

    int max = Integer.MAX_VALUE;
    for (int i = 1; i <= n; i++) {
      int tmp = x + i;
      if (!ps.contains(tmp)) {
        max = tmp;
        break;
      }
    }
    int min = Integer.MAX_VALUE;
    for (int i = 1; i <= n; i++) {
      int tmp = x - i;
      if (tmp < 0) {
        break;
      }
      if (!ps.contains(tmp)) {
        min = tmp;
        break;
      }
    }

    if (Math.abs(x - min) <= Math.abs(x - max)) {
      System.out.println(min);
    } else {
      System.out.println(max);
    }
  }
}