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: Wrong Answer)

using System;
using System.Linq;

class Project
{
    static void Main(string[] args)
    {
        string[] input = Console.ReadLine().Split(' ');
        int X = int.Parse(input[0]);
        int N = int.Parse(input[1]);

        if(N == 0)
        {
            Console.WriteLine(X);
            return;
        }

        else
        {
            int[] A = Console.ReadLine().Split(' ').Select(s => Int32.Parse(s)).ToArray();
            if (!A.Contains(X))
            {
                Console.WriteLine(X);
                return;
            }

            int[] c = new int[100];
            int i, j, max = 0, min = 0;
            for (i = 0; i < 100; i++)
            {
                c[i] = i + 1;

                for (j = 0; j < N; j++)
                {
                    if (c[i] == A[j])
                    {
                        c[i] = 0;
                    }
                }

                if (c[i] != 0 && (i == 0 || X - c[i] > 0 && c[i] > max))
                {
                    max = c[i];
                }
                else if (c[i] != 0 && (i == 0 || X - c[i] < 0 && min == 0))
                {
                    min = c[i];
                }

            }

            if ((X - max) + (X - min) == 0 || (X - max) + (X - min) < 0)
            {
                Console.WriteLine(max);
            }
            else
            {
                Console.WriteLine(min);
            }
        }

        

    }
}