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;
class Program
{
	static void Main()
	{
        string[] a = Console.ReadLine().Split(' ');
		int b = int.Parse(a[0]);
		int c = int.Parse(a[1]);
        if(c == 0)
        {
            Console.WriteLine(b);
            return;
        }

        if(c == 1)
        {
            if(int.Parse(Console.ReadLine()) != b)
            {
                Console.WriteLine(b);
            }
            else
            {
                Console.WriteLine(b - 1);
            }
            return;
        }

        string[] d = Console.ReadLine().Split(' ');
        int[] e = Array.ConvertAll(d, int.Parse);

        if(!(Array.IndexOf(e, b) > 0))
        {
            Console.WriteLine(b);
            return;
        }

        int f = b, g = b; 
        for(int i=0; i<c+1; i++)
        {
            f -= 1;
            if(!(Array.IndexOf(e, f) > 0))
            {
                Console.WriteLine(f);
                return;
            }

            g += 1;
            if(!(Array.IndexOf(e, g) > 0))
            {
                Console.WriteLine(g);
                return;                
            }

        }
	}
}