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: Accepted)

using System;
using System.Linq;

public class Test
{
	public static void Main()
	{
		var line0 = Console.ReadLine().Split(new char[]{' '}).Select(c => Int32.Parse(c)).ToArray();
		var x = line0[0];
		var n = line0[1];
		if (n == 0)
		{
			Console.WriteLine(x);
		}
		else
		{
		var line1 = Console.ReadLine().Split(new char[]{ ' '}).Select(c => Int32.Parse(c)).ToArray();
		var found = false;
		var offset = 0;
		while(!found)
		{
			var x0 = x + offset;
			var x1 = x - offset;
			if (!line1.Any(a => x1 == a))
			{
				found = true;
				Console.WriteLine(x1);
			}
			else if (!line1.Any(a => x0 == a))
			{
				found = true;
				Console.WriteLine(x0);
			}
			offset++;
		}
		}
	}
}