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.Linq;

class IDONTKNOWCSHARP
{
    public static void Main()
    {
        string[] values = Console.ReadLine().Split(new string[] { " " }, StringSplitOptions.RemoveEmptyEntries);
        int X = int.Parse(values[0]);
        int N = int.Parse(values[1]);

        int[] nums = Convert(Console.ReadLine().Split(new string[] { " " }, StringSplitOptions.RemoveEmptyEntries));

        int kouho1, kouho2;

        int temp = 0;
        while (true)
        {
            if (!nums.Contains(X - temp))
            {
                kouho1 = X - temp;
                break;
            }

            temp++;
        }

        temp = 0;
        while (true)
        {
            if (!nums.Contains(X + temp))
            {
                kouho2 = X + temp;
                break;
            }

            temp++;
        }

        if (Math.Abs(kouho1 - X) > Math.Abs(kouho2 - X))
        {
            Console.WriteLine(kouho2 );
        }
        else
        {
            Console.WriteLine(kouho1 );

        }
    }

    static int[] Convert(string[] v)
    {
        var temp = new int[v.Length];

        for (int i = 0; i < temp.Length; i++)
        {
            temp[i] = int.Parse(v[i]); 
        }

        return temp;
    }

}