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.*;

public class Main {
    public static void main(String args[]){
        Scanner stdIn = new Scanner(System.in);
        
        int x = stdIn.nextInt();
        int n = stdIn.nextInt();
        
        boolean flag[] = new boolean[501];
        
        for(int i = 0; i < 501; i++){
            flag[i] = true;
        }
        
        for(int i = 0; i < n; i++){
            flag[250 + stdIn.nextInt()] = false;
        }
        
        
        if(n != 0){
            if(flag[250 + x] != true){
                for(int i = 1; ; i++){
                    if(flag[250 + x - i] == true){
                        System.out.println(x - i);
                        break;
                    }
                    
                    if(flag[250 + x + i] == true){
                        System.out.println(x + i);
                        break;
                    }
                }
            }else{
                System.out.println(x);
            }
        }else{
            System.out.println(x);
        }
        
    }
}