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.*;
public class Main {
    public static void main(String[] args){
        Scanner sc = new Scanner(System.in);
      
      //入力
      int x =sc.nextInt();//整数
      int n =sc.nextInt();//数列の長さ
      int ans = 0;
      int min = 100;
      
      //数列listの空箱用意
      List<Integer> s = new ArrayList<Integer>();
      
      //数列のlist作成
      for(int i =0; i<n; i++){
      		s.add(sc.nextInt());
      } 
      //数列がないとき
		if(n == 0 || !(s.contains(x))) {
			System.out.println(x);
		}
      
      	else {
			for(int i =0; i<=100; i++) {
                //数列に含まれていない整数か
				if(!(s.contains(i))) {
                    //絶対値が小さい整数を求める
					if(Math.abs(x - i) < min) {
                        //最小値を更新する
						min = Math.abs(x - i);
						ans = i;
                    }
                }
            }
          System.out.println(ans);
        }
    }
}