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 OCaml (4.10.0) (judge verdict: Wrong Answer)

let ($) f g = fun x -> g (f x)
let split_string ?(pattern="") = Str.split @@ Str.regexp pattern
let (x, n) = Scanf.sscanf (read_line ()) "%d %d" @@ fun x n -> (x, n)
let p = read_line () |> split_string ~pattern:" " |> List.map int_of_string

let () =
  Printf.printf "%d\n" @@ 
    if n = 0 then x
    else Array.init 102 (fun i -> i - 1)
      |> Array.to_list
      |> List.filter (fun i -> not (List.mem i p))
      (* |> (fun acc -> List.iter (Printf.printf "%d ") acc; acc) *)
      |> List.map (fun i -> (abs (i - x), i))
      |> List.sort compare
      |> (List.hd $ snd)