mars\Exercise01.class
....\Exercise01.java
....\Exercise01.java.bak
....\Exercise02.class
....\Exercise02.java
....\Exercise02.java.bak
....\Exercise03.java
....\Exercise03.java.bak
....\Exercise04.class
....\Exercise04.java
....\Exercise04.java.bak
....\HelloWorld.class
....\HelloWorld.java
....\HelloWorld.java.bak
mars