maybe 99... or 100... i don't know if my hypothesis is correct but in the LMS Event you can't participate unless you're level is 900-999... maybe you can enter it if you're level is 899 because can't be attacked by other players
oh i forgot... i think if you are in a PK map... (PvP For Example) it won't matter if your level is 1. other players can attack you i think