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)

/******************************************************************************

                            Online Java Compiler.
                Code, Compile, Run and Debug java program online.
Write your code in this editor and press "Run" button to execute it.

*******************************************************************************/
import java.util.*;
public class Main
{
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int k = sc.nextInt();
		int n = sc.nextInt();
		if(n == 0)
		System.out.println(k);
		else
		{
		    HashSet<Integer> st = new HashSet<Integer>();
		    int[]a = new int[n];
		    int i;
		    for(i=0; i<n; i++)
		    {
		        a[i] = sc.nextInt();
		        st.add(a[i]);
		    }
		    int min = 999,val=0;
		    Arrays.sort(a);
		    for(i=a[0]; i<a[n-1]; i++)
		    {
		        if(!st.contains(i))
		        {
		            int x = k - i;
		            if(x < 0)
		            {
		                x = x * (-1);
		            }
		            if(x < min)
		            {
		                val = i;
		                min = x;
		            }
		        }
		    }
		    if(val == 0)
		    {
		        val = a[n-1] + 1;
		    }
		    System.out.println(val);
		}
	}
}