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.Scanner;
import java.util.Set;
import java.util.HashSet;

public class Main {
    public static void main(String[] args) {

        Scanner sc = new Scanner(System.in);
        int target = Integer.parseInt(sc.next());
        int count = Integer.parseInt(sc.next());
        Set<Integer> nums = new HashSet<Integer>();
        for (int i = 0; i < count; i++) {
            nums.add(Integer.parseInt(sc.next()));
        }

        if (nums.size() == 0) {
            System.out.println(target);
            return;
        }

        for (int i = 1; i <= 100; i++) {

            if ((target - i) > 0) {
                if (!nums.contains((target - i))) {
                    System.out.println(target - i);
                    return;
                }
            }

            if ((target + i) <= 100) {
                if (!nums.contains((target + i))) {
                    System.out.println(target + i);
                    return;
                }
            }

        }
        System.out.println(0);
        sc.close();
    }
}