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.Arrays;
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 scan = new Scanner(System.in);
		
		int x = scan.nextInt();
		int n = scan.nextInt();
		long[] list = new long[n];
		
		
		for(int i = 0; i < n; i++) {
			list[i] = scan.nextInt();
		}
		Arrays.sort(list);
		
		long small = 1000;
		long ans = 0;
		long num = 0; 
		boolean judge = false;
		boolean zero = false;
		boolean one = false;
		
		if(n != 0) {
		if(list[n-1] > x) {
			judge = true;
		}else if(list[n-1] < x){
			zero = true;
		}else if(list[0] > x) {
			zero = true;
		}else if(list[0] < x) {
			judge = true;
		}
		/*
		else if(list[n-1] == x) {
			if(list[n-2] == list[n-1] - 1) {
				one = true;
			}
		}*/
		
		
		for(long i = list[0]; i < list[n-1]; i++) {
			boolean skip = false;
			for(int j = 0; j < n; j++) {
				if(i == list[j]) {
					skip = true;
					break;
				}
			}
			if(skip == true) {
				continue;
			}
			
			if(i > 0 && i < x) {
				ans = x - i;
			}
			else if(i > 0 && i > x) {
				ans = i - x;
			}
			else if(i == 0) {
				ans = x;
			}
			else if(i < 0) {
				ans = x + i;
				if(ans < 0) {
					ans = -1 * ans;
				}
			}
			
			if(ans < small) {
				small = ans;
				num = i;
			}
			
		
	}
		if(judge == true) {
		System.out.print(num);
		}
		else if(zero == true) {
			System.out.print(x);
		}
		}
		else {
			System.out.print(x);
		}

}
}