<?php

$t0 = microtime(true);

for ($i = 0; $i < 1000000; $i++) {
	$str = sprintf("23456789ABCDEGHJKMNPQRSTUVXYZabcdeghjkmnpqrstuvxyz%06d", 0);
    if (preg_match('/cp|cb|ck|c6|c9|rn|rm|mm|co|do|cl|db|qp|qb|dp|ww/', $str))
        break;
}

$t1 = microtime(true);

for ($i = 0; $i < 1000000; $i++) {
    $str = sprintf("23456789ABCDEGHJKMNPQRSTUVXYZabcdeghjkmnpqrstuvxyz%06d", $i);
    if (preg_match('/cp|cb|ck|c6|c9|rn|rm|mm|co|do|cl|db|qp|qb|dp|ww/', $str))
        break;
}

$t2 = microtime(true);

echo "const string: " . ($t1 - $t0) . " sec\n";
echo "dynamic string: " . ($t2 - $t1) . " sec\n";