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-mcs 6.8.0.105) (judge verdict: Wrong Answer)

using System;
using static System.Console;
using static System.Math;


namespace AtCoder
{
    public class Program
    {
        public static void Main(string[] args)
        {
            int ans = 0;
            var s = ReadLine().Split(' ');
            int X = int.Parse(s[0]);
            int N = int.Parse(s[1]);
            if (N == 0)
            { ans = X; }
            else
            {
                s = ReadLine().Split(' ');
                int[] p = new int[N];

                bool a = false;
                for (int i = 0; i < N; i++)
                { p[i] = int.Parse(s[i]); }

                for (int i = 0; i < 100; i++)
                {
                    a = true;
                    for (int j = 0; j < N; j++)
                    {
                        if (p[j] == X + i)
                        {
                            a = false;
                            break;
                        }
                        ans = X + i;
                        if (p[j] == X - i)
                        {
                            a = false;
                            break;
                        }
                        ans = X - i;

                    }
                    if (a == true)
                    { break; }
                }
            }


            WriteLine(ans);
        }
    }

    public static class MyMath
    {
        public static long Factorical(long n)
        { return n <= 1 ? 1L : n * Factorical(n - 1); }
        public static long Permutation(long n, long m)
        { return Factorical(n) / Factorical(n - m); }
        public static long Combination(long n, long m)
        { return Permutation(n, m) / Factorical(m); }
        public static long Gcd(long n, long m)
        { return n % m == 0 ? m : Gcd(m, n % m); }
        public static long Pow(long n, long m)
        { return (m == 1 || m == 0) ? 1L : n * Pow(n, m - 1); }
    }

}