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 Lua (LuaJIT 2.1.0) (judge verdict: Accepted)

local read = io.read
local insert = table.insert
local abs = math.abs

local X, N = read("*n", "*n")
local p = {}
for i = 1, N do
	p[i] = read("*n")
end

local not_p = {}
for i = 0, 101 do
	local can_ins = true
	for j = 1, N do
		if p[j] == i then
			can_ins = false
			break
		end
	end
	if can_ins then
		insert(not_p, i)
	end
end

local out = math.huge
for i = 1, #not_p do
	if abs(not_p[i] - X) < abs(out - X) then
		out = not_p[i]
	end
end

print(out)