/**
* Generate new cpid for contest
* @global type $conn
* @param type $cid
* @return type new unused cpid
*/
function gen_new_cpid($cid)
{
global $conn;
$rs = new RecordSet($conn);
$rs->Query("SELECT * FROM contest_problems WHERE cid='{$cid}'");
$problems_n = $rs->num_rows() + 1000;
return $problems_n;
}