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)

input = STDIN.gets.split(" ").map do |x| x.to_i end
data = STDIN.gets.split(" ").map do |x| x.to_i end
x = input[0]
n = input[1]

#p x
#p n
#p data

if (n == 0) then
  puts(x)
  exit
end

nums = Array.new(100)
for i in -100..100 do
  nums[i] = i
end

data.each do |p|
  nums[p] = nil
end

#p nums

diff = -1
while (diff > -100) do
#puts("CHECK")
#p x+diff
  if (nums[x + diff] != nil) then
    puts(nums[x+diff])
    exit
  end
#p x+diff*(-1)
  if (nums[x + diff * (-1)] != nil) then
    puts(nums[x+diff * (-1)])
    exit
  end

  diff -= -1
end