O2Jam Extra Class

okay~ Before I go on with the main topic, here's the layout of my NEW timetable. (I dropped 2 subjects and took 2 new ones)

Mon- 12pm~2pm, 2pm~5pm
Tues- 10am~12pm, 4pm~6pm
Wed- 2pm~4pm
Thus- 4pm~6pm
Fri- 2.30pm~3.30pm

Yea... still have 4 hours gap but it's not monday~ but then again... Monday is 5 hours straight T.T

on with my rantings~ It seems that due to the Wesak Day holiday on monday, my 2 hour class is to be replaced on May 28th. The SAME DAY as the O2Jam Gathering which I was looking forward to since last month.
The gathering starts at 11am~6pm
Extra class, 10am~12pm

So what can I do?? Skip the darn class.... T.T ? or be late and lose out on lots of events and prizes
No doubt I'll be missing some stuff but I should be able to catch up on stuff (hopefully no pop quizzes). O2jam gathering was announced to me first before the extra class.... but I feel so guilty =.=

O2Jam gathering : Get to see friends, have fun, free song, free gifts, new friends, ONCE in a YEAR event
Extra class : Quizzes, attendance, good grades, boredom?, affects my grades, etc

Which =.=?????