Check your instructions for a statement similar to:
When you submit your assignment, each part (client and server) must be executable using a command of this exact form:
Your programs must not require use of command line arguments other than the single mode flag, which must be supported. Your programs must not require use of command line property specifications. All configuration must be done via a GUI, and must be persistent between runs of the program. Such configuration information must be stored in a file called suncertify.properties which must be located in the current working directory.
The mode flag must be either "server", indicating the server program must run, "alone", indicating standalone mode, or left out entirely, in which case the network client and gui must run.
Note: Highlighting is mine.
So for server mode, you must enter java -jar runme.jar server.