Array Manipulator

<?php
$input = trim(fgets(STDIN));
$numbers = explode(" ", $input);

while (true) {
    $input = trim(fgets(STDIN));
    if ($input == "print") break;

    $command = explode(" ", $input);
    switch ($command[0]) {
        case "add" :
            if ($command[1] <= count($numbers))
                array_splice($numbers, $command[1], 0, $command[2]);
            break;
        case "addMany" :
            if ($command[1] <= count($numbers))
                array_splice($numbers, $command[1], 0, array_slice($command, 2));
            break;
        case "contains" :
            $found = array_search($command[1], $numbers);
            echo ($found === false ? -1 : $found) . "\n";
            break;
        case "remove" :
            if ($command[1] < count($numbers))
                array_splice($numbers, $command[1], 1);
            break;
        case "shift" :
            while (true) {
                $numbers = array_merge(array_slice($numbers, $command[1], NULL, true), array_slice($numbers, 0, $command[1], true));
                $command[1] -= count($numbers);
                if ($command[1] < 0) break;
            }
            break;
        case "sumPairs" :
            for ($i = 0; $i < count($numbers); $i++) {
                if (key_exists($i + 1, $numbers)) {
                    $numbers[$i] += $numbers[$i + 1];
                    array_splice($numbers, $i + 1, 1);
                }
            }
            break;
    }
}
echo "[" . implode(", ", $numbers) . "]";