Fatal error: Uncaught Error: Class 'mysqli' not found in /home/itolympc/contest.itolymp.com/classes/mysql.class:24 Stack trace: #0 /home/itolympc/contest.itolymp.com/classes/user.class(5): require_once() #1 /home/itolympc/contest.itolymp.com/header_lite.php(2): require_once('/home/itolympc/...') #2 /home/itolympc/contest.itolymp.com/index.php(1): include('/home/itolympc/...') #3 {main} thrown in /home/itolympc/contest.itolymp.com/classes/mysql.class on line 24