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 Common Lisp (SBCL 2.0.3) (judge verdict: Runtime Error)

(defun split-and-parse-integer (string)
  (loop for i = 0 then (1+ j)
    as j = (position #\Space string :start i)
    collect (parse-integer (subseq string i j))
    while j))
(defparameter x (read))
(defparameter n (read))
(defparameter lst (split-and-parse-integer (read-line)))
(defparameter ans 1)
(defparameter tmp 100)

(loop for i below 100
     do (if (and (not (find i lst)) (> tmp (abs (- x i))))
            (progn (setf ans i)
            (setf tmp (abs (- x i))) )
            )
      )

(princ ans)