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 program{
  static void Main(){
    byte[] xn = Array.ConvertAll(Console.ReadLine().Split(' '),byte.Parse);
    if(xn[1] == 0){
      Console.Write(xn[0]);
      Environment.Exit(0);
    }
    byte[] p = Array.ConvertAll(Console.ReadLine().Split(' '),byte.Parse);
    bool[] table = new bool[201];
    for(byte i = 0;i<xn[1];i++){
      table[p[i]] = true;
    }
    if(!table[xn[0]]){
      Console.Write(xn[0]);
      Environment.Exit(0);
    }
    for(byte i = 1;i < 200;i++){
      if(xn[0] >= i){
      	if(!table[xn[0]-i]){
          Console.Write(xn[0]-i);
          break;
        }
      }
      if(!table[xn[0]+i]){
        Console.Write(xn[0]+i);
        break;
      }
    }
  }
}