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: Wrong Answer)

X,N = gets.strip.split(nil).map(&:to_i)
if N == 0 then
  m = X
else
  numbers = gets.strip.split(nil).map(&:to_i)
  i = 0
  numbers.any? {|x| x == X}
  if true then
    i += 1
  else
    m = X
  end
  while i >= 1 do
    hokaku = numbers.select{|x| (x-X).abs == i}
      if hokaku.size == 2
        i += 1
      elsif hokaku.size == 1
        if hokaku[0] == X-i then
          m = X+i
        else
          m = X-i
        end
        break
      else
        m = X-i
        break
      end
  end
end
puts m