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 sc = new Scanner(System.in);
		// 整数の入力
		int a = sc.nextInt();
		// スペース区切りの整数の入力
		int b = sc.nextInt();
      	if(b != 0){
      		int c [] = new int[b];
      		for(int i = 0; i < b; i++){  
      			c [i] = sc.nextInt();
      		}
      	int d = -1;
        boolean f = true;
        boolean g = true;
		boolean h = true;
		// 出力
     	while(f && h){
        	f = false;
            h = false;
            d ++;
       		 for(int i = 0; i < b; i++){
     		 	if(( c[i] - a ) == d){
         			f = true;
         		}
               if(( c[i] - a ) == -d){
         			h = true;
         		}
     		}
        }
             for(int i = 0; i < b; i++){
     		 	if( c[i] - a  ==  -d){
         			g = false;
         		}
     		}
       if(g){
    	System.out.println(a - d);   	
       }else{
       	System.out.println(a + d);
       }
	
      } 
      else{
      	System.out.println( a );
      }
	}
}