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
    list($X,$N) = array_map('intval',explode(" ",trim(fgets(STDIN))));
    
    //$N==0の時2行目が空行となるので＄Xをそのまま表示して終わり
    if($N == 0){
        echo $X."\n";
        exit;
    }
    
    $array = array_map('intval',explode(" ",trim(fgets(STDIN))));
    
    //被検索対象の数字の中に検索したい数字がなければ検索したい数字で決定して終わる
    if(!in_array($X,$array)){
        echo $X."\n";
    }
    
    sort($array);
    
    //ここに来たということは検索する数字が文字列に存在しているのでその数字を
    //1ずつ増減させて調べていく
    for($i=1;$i<=100;$i++){
        $A = $X - $i;
        $B = $X + $i;
        //存在しない数字があった瞬間決定する
        if(in_array($A,$array)==0 && $A>=1){
            // echo array_search($A,$array);
            // print_r($array);
            // echo "a\n";
            echo $A."\n";
            exit;
        }
        if(in_array($B,$array)==0 && $B<=100){
            // echo "b\n";
            echo $B."\n";
            exit;
        }
        
    }

?>