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: Runtime Error)

import java.util.Arrays;
import java.util.Scanner;
public class Main {
	public static void main(String[] args) {
		Scanner stdIn = new Scanner(System.in);
	
		int x = stdIn.nextInt();
		
		int n = stdIn.nextInt();
		
		if(n == 0) {
			System.out.println(x);
			return;
		}
		
		
		
		int[] p = new int[n];
		
		boolean[] num = new boolean[100];
		
		for(int i = 0; i < n; i++) {
			p[i] = stdIn.nextInt();
			num[p[i]] = true;
		}
		
		Arrays.parallelSort(p);	
		
		int a = Integer.MAX_VALUE;
		int b = Integer.MAX_VALUE;
		
		for(int i = x; i >= -10; i--) {
			if(!num[i]) {
				a = i;
				break;
			}
		}
		
		for(int i = x; i <= 103; i++) {
			if(!num[i]) {
				b = i;
				break;
			}
		}
		
		//int ans = Math.min(Math.abs(x-a), Math.abs(x-b));
		
		if(Math.abs(x-a) <= Math.abs(x-b)) {
			System.out.println(a);
		}else {
			System.out.println(b);
		}
		
		
	}
}