<?php
if (isset($_GET['commands'])&&isset($_GET['delimiter'])){

    $command= $_GET['commands'];
    $delimiter = $_GET['delimiter'];
    $command = explode("\n", $command);
    $command = array_map('trim', $command);

    $result=[];

    for($i=0; $i<sizeof($command); $i++){

        $parts = explode($delimiter, $command[$i]);

        if($parts[0] == "add"){
            $result[$i] = $parts[1];
        }
        else if($parts[0]== "remove"){
            array_splice($result,$parts[1],1);
        }

    }

for($i=0; $i<sizeof($result); $i++){
    echo $result[$i]."<br>";
}

}

?>