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: Wrong Answer)

(defun main(x n)
    (let ((a (make-array n :initial-element 0))
        (b 0)
        (ans T))

        (if (= n 0)
            (setq b x))
    
        (dotimes (i n)
            (setf (aref a i) (read))
        )

        (dotimes (i n)
            (if (= x (aref a i))
                (setf ans Nil))
        )
        (if (not (eq ans Nil))
            (setq b x)
            (setf ans T)
        )

        (if (= b 0)
            (loop named main-loop for i from 1 to 101
                do (progn    
                (if (and (< 0 (- x i)) (eq ans T))
                    (progn
                    (setq b (- x i))
                    (dotimes (j n)
                        (if (= (- x i) (aref a j))
                            (setf ans Nil)))
                    (if (equal ans T)
                        (return-from main-loop)
                        (setf ans T))
                    )
                )
                )
                (if (and (> 101 (+ x i)) (eq ans T))
                    (progn
                    (setq b (+ x i))
                    (dotimes (j n)
                        (if (= (+ x i) (aref a j))
                            (setf ans Nil)))
                    (if (equal ans T)
                        (return-from main-loop)
                    (setf ans T))
                    )
                )

            )
        )
    b)

)
(format t "~D~%" (main (read) (read)))