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)

x, n = gets.split(" ").map(&:to_i)
array = gets.split(" ").map(&:to_i)

if !array.include?(x)
  puts x
  exit
end

nums = []
for i in (x + 1)..101
#   puts "#{i}  #{(x - i).abs}"
#   p !array.include?(i)
  if !array.include?(i)
    nums << [i, (x - i).abs]
    break
  end
end

i = 0
while i < x
#   puts "#{x - 1 - i}  #{(x - 1 - i - x).abs}"
#   p !array.include?(x - 1 - i)
  if !array.include?(x - 1 - i)
    nums << [(x - 1 - i), (x - 1 - i - x).abs]
    break
  end
  i += 1
end

puts nums.sort_by{|item| [item[1], item[0]]}[0][0]