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: Accepted)

using System;
using System.Collections.Generic;
using System.Text;

namespace ABC0613
{
    class Program
    {
        static void Main(string[] args)
        {
            string[] inp = Console.ReadLine().Split(' ');
            int ans = int.MaxValue;
            if(inp[1]=="0")
            {
                ans = int.Parse(inp[0]);
            }
            else
            {
                int x = int.Parse(inp[0]);
                int n = int.Parse(inp[1]);
                string[] array = Console.ReadLine().Split(' ');
                List<int> list = new List<int>();

                foreach(string str in array)
                {
                    int hoge = int.Parse(str);
                    list.Add(hoge);
                }

                for(int i=0;i<1000;i++)
                {
                    int temp = x - i;
                    if(!list.Contains(temp))
                    {
                        ans = temp;break;
                    }
                    temp = x + i;
                    if (!list.Contains(temp))
                    {
                        ans = temp; break;
                    }
                }

            }
            
            Console.WriteLine(ans);
        }
    }
}