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 C# (.NET Core 3.1.201) (judge verdict: Runtime Error)

using System;
//using System.Collections;
using System.Collections.Generic;
using System.Linq;

namespace Abc170
{
    class MainClass
    {

        public static void Main(string[] args)
        {

            
            var answerList = new List<int>();

            int answer = 100;
            int answer1 = 0;

            string p0 = "";
            int[] inputXNArray = Console.ReadLine().Split(' ').Select(i => int.Parse(i)).ToArray();
            try
            {
                var p = Console.ReadLine();
                p0 = p;
            }
            catch(FormatException)
            {
                p0 = "0";
            }

            int[] inputPArray = p0.Split(' ').Select(i => int.Parse(i)).ToArray();


            for (int i = 1; i < 101; i++)
                {
                        if (inputPArray.Contains(i))
                        {

                        }
                        else
                        {
                            if (Math.Abs(i - inputXNArray[0]) < answer)
                            {
                                answer1 = i;
                                answer = Math.Abs(i - inputXNArray[0]);

                            }
                        }

                }

            
            if(answer1 != 0)answerList.Add(answer1);

            foreach(int i in answerList)
            {
                Console.WriteLine(i+" ");
            }
        }
    }
}