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.*; 
import java.lang.*; 


public class Main{
	public static void main(String[] args){
		Scanner scan = new Scanner(System.in);
                
                int X = scan.nextInt();
                int N = scan.nextInt();
                
                int min1=-1;
                ArrayList<Integer> list = new ArrayList<>();
                for(int i=-1; i<=101; i++){
                    list.add(i);
                }       
                for(int i=0; i<N;i++){
                    int p = scan.nextInt();
                    for(int j=0; j<list.size(); j++){
                        if(p==list.get(j)){
                            list.remove(j);
                            break;
                        }
                    }
                }
                int sa = 1000;
                int ans = -1;
                for(int i=0; i<list.size();i++){
                     if(sa>Math.abs(X-list.get(i))){
                         sa = Math.abs(X-list.get(i));
                         ans = list.get(i);
                     }
                }
                
                System.out.println(ans);
        }
}