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.*;
import java.lang.Math.*;
import java.util.Arrays;
import java.util.Collections;
public class Main {
	public static void main(String[] args){
		Scanner sc = new Scanner(System.in);
		// スペース区切りの整数の入力
      int x=sc.nextInt();
      int n=sc.nextInt();
      int bigans=x;
      int smlans=x;
      Integer ns[]=new Integer[n];
      for(int i=0;i<n;i++){
        ns[i]=sc.nextInt();
      }
      Arrays.sort(ns);
      for(int i=0;i<n;i++){
        int nx=ns[i];
        if(bigans==nx){
          bigans=nx+1;
        }
      }
      Arrays.sort(ns, Collections.reverseOrder());
      for(int i=0;i<n;i++){
        int nx=ns[i];
         if(smlans==nx){
          smlans=nx-1;
        }
      }
      if(Math.abs(smlans-x)<Math.abs(bigans-x)){
        System.out.println(smlans);
      }else{
        System.out.println(bigans);
      }
}
}