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;

class Program
{
	static void Main(string[] args)
	{
		string[] input_1 = Console.ReadLine().Split(' ');
		string[] input_2 = Console.ReadLine().Split(' ');


		if(int.Parse(input_1[1]) == 0)
        {
			Console.WriteLine(int.Parse(input_1[0]));
        }
        else
        {
			int numX = int.Parse(input_1[0]);
			bool isOutput = false;
			bool isSame = false;

			for(int i = 0;i < 100; i++)
            {
				if (isOutput) break;

				isSame = false;
				foreach (string s in input_2)
                {
                    if ((numX - i) == int.Parse(s)){
						isSame = true;
                    }
                }

                if (!isSame)
                {
					Console.WriteLine(numX - i);
					isOutput = true;
				}

				if (isOutput) break;
				isSame = false;
				foreach (string s in input_2)
                {
                    if ((numX + i) == int.Parse(s)){
						isSame = true;
                    }
                }

                if (!isSame)
                {
					Console.WriteLine(numX + i);
					isOutput = true;
				}
			}
        }
	}
}