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 PHP (7.4.4) (judge verdict: Wrong Answer)

<?php
 
fscanf(STDIN, "%d %d", $x, $n);

if ($n == 0) {
  echo($x);
  exit;
}

$N_array = trim(fgets(STDIN));
$N_array = explode(" ", $N_array);

for($i=1;$i <= $n + 1;$i++) {
 	if ($i % 2 == 1) {
      $r = $x - ((int)($i / 2) + 1);
    } else {
      $r = $x + (int)($i / 2);
    }
    if (!in_array($r, $N_array)) {
        echo($r);
        exit;
    }
}