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: Accepted)

import java.util.Arrays;
import java.util.List;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		// TODO 自動生成されたメソッド・スタブ

		Scanner sc = new Scanner(System.in);
		int x = sc.nextInt();
		int n = sc.nextInt();
		Integer[] array = new Integer[n];
		for(int i=0;i<n;i++) {
			array[i] = sc.nextInt();
		}
		sc.close();

		Arrays.sort(array);
//		for(int a : array) {
//			System.out.println(a);
//		}

		List<Integer> list = Arrays.asList(array);
		if(!(list.contains(x))) {
			System.out.println(x);
			return;
		}

		int ans=10000000;
		for(int i=1;i<=100;i++) {
			int min1 = Math.abs(x-i);
			if(!(list.contains(min1))) {
				System.out.println(min1);
				return;
			}
			int max1 = x+i;
			if(!(list.contains(max1))) {
				System.out.println(max1);
				return;
			}
		}

	}
}