Dear Colleagues,

It's occurring a weird situation: on my notebook, compiling using this Online Judge way, my java code for this problem works fine and gives the correct answers. When i submit it, however, online judge accuses of "Runtime Error". It follows below my "java version":

"java version "1.7.0_01" # At Ubuntu 11.10
Java(TM) SE Runtime Environment (build 1.7.0_01-b08)
Java HotSpot(TM) 64-Bit Server VM (build 21.1-b02, mixed mode)"

Can anyone explain why "Runtime Error" in Online Judge?