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 sn = new Scanner(System.in);
        int X = sn.nextInt();
        int N = sn.nextInt();
        List<Integer> pList = new ArrayList<>();

        if(N == 0) System.out.println(X);
        else{
            for(int i=0; i<N; i++){
                pList.add(sn.nextInt());
                }

            Arrays.asList(pList);
            int u_i = X;
            int d_i = X;

            while(true){
                if(!pList.contains(u_i) && !pList.contains(d_i)){
                    System.out.println(d_i);
                    break;
                }
                else if(!pList.contains(u_i)){
                    System.out.println(u_i);
                    break;
                }
                else if(!pList.contains(d_i)){
                    System.out.println(d_i);
                    break;
                }

                u_i++;
                d_i--;
            }
        }
    }
}