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# (Mono-csc 3.5.0) (judge verdict: Wrong Answer)

using System;
using System.Collections.Generic;
using System.Linq;
public class GFG
{
    class Pair
    {
        public int Num;
        public int diff;
    }
    public static void Main()
    {

        var input = Console.ReadLine().Split(' ');

        var X = int.Parse(input[0]);
        var n = int.Parse(input[1]);
        List<Pair> ans = new List<Pair>();
        if (n == 0)
        {
            Console.Write(X);
            return;
        }
        var arr = Console.ReadLine().Split(' ').Select(x => int.Parse(x)).ToArray();
        int max = arr.Max();
        int[] ansArr = new int[1000];
        for (int i = 0; i < n; i++)
        {
            ansArr[arr[i]] = 1;
        }
        for (int i = 0; i < 1000; i++)
        {
            if (ansArr[i] == 0 && i > 0)
            {
                Pair p = new Pair();
                p.Num = i;
                p.diff = Math.Abs(X - i);
                ans.Add(p);
            }
        }

        var res = ans.OrderBy(x => x.diff).ThenBy(x => x.Num).Take(1).SingleOrDefault();
        Console.Write(res.Num);
    }


}