Hádanie náhodného čísla v PHP

<?php
/**
 * @author sczdavos
 * @site www.itnetwork.cz
 */

header('Content-type: text/html; charset=utf8');

if ((isset($_POST['number'])) && ($_POST['number']))
    $number = $_POST['number'];
else
    $number = rand(0, 200);
$tries = 0;

if (isset($_POST['user_number']))
{
    $tip = $_POST['user_number'];
    $tries = $_POST['tries'] + 1;
    $diff = abs($tip - $number);

    if ($diff > 50)
        echo('Hodně vedle');
    else if (($diff <= 50) && ($diff >= 21))
        echo('Vedle');
    else if (($diff <= 20) && ($diff >= 6))
        echo('Přihořívá');
    else if (($diff <= 5) && ($diff >= 1))
        echo('Těsně vedle');
    else
        echo('Trefa');

    echo('Pokus číslo: ' . $tries);
}

echo('
    <form method="post">
        <input type="hidden" name="number" value="' . $number . '" />
        <input type="hidden" name="tries" value="' . $tries . '" />
        <input type="text" name="user_number" />
        <input type="submit" />
    </form>
');