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 1.8.0) (judge verdict: Accepted)

import java.util.Scanner;
import java.util.ArrayList;

public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);

    //input
    int x = sc.nextInt();
    int n = sc.nextInt();
    ArrayList<Integer> intArray = new ArrayList<Integer>();
    for(int i = 0; i < n; i++){
      intArray.add(sc.nextInt());
    }

    //output
    if( n == 0 ){
      System.out.println(x);
    }else{

      for(int i = 0; i < 1000; i++){

        if( i == 0 ){
          boolean found = false;
          for(int j = 0; j < intArray.size(); j++){
            if( intArray.get(j) == x ){
              intArray.remove(j);
              found = true;
              break;
            }
          }
          if( !found ){
            System.out.println(x);
            break;
          }
        }else{
          boolean highExist = false;
          boolean lowExist = false;
          for(int j = 0; j < intArray.size(); j++){

            if( intArray.get(j) == x+i ){
              highExist = true;
              intArray.remove(j);
              j--;
            }else if( intArray.get(j) == x-i ){
              lowExist = true;
              intArray.remove(j);
              j--;
            }

            if( highExist && lowExist ){
              break;
            }

          }
          if( !(highExist && lowExist) ){
            if( highExist ){
              System.out.println(x-i);
              break;
            }else if( lowExist ){
              System.out.println(x+i);
              break;
            }else{
              System.out.println(x-i);
              break;
            }
          }
        }

      }

    }

  }
}