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 Ruby (2.7.1) (judge verdict: Accepted)

input = readlines()

meta = input.shift.chomp.split("\s").map{|x| x.to_i}

target_num = meta[0]

forbid_list = input.shift.split("\s").map{|x| x.to_i}

nearlest = nil
n_abs = nil
(-100..200).each do |x|
  next if forbid_list.include?(x)
  c_abs = (target_num - x).abs
  if n_abs.nil? || c_abs <= n_abs
    if n_abs.nil? || c_abs < n_abs
      nearlest = x
      n_abs = c_abs
      next
    end
    if c_abs == n_abs && nearlest > x
      nearlest = x
      n_abs = c_abs
    end
  end
end

puts nearlest