# Changes for 2005

1. Java 1.5 or higher is required.

2. Since Java 1.5 directly provides advanced formatted I/O, the ACMIO class will not be provided.

3. Windows-based sites are required to provide Windows 2000 or higher (9x/ME/NT will not be allowed). Mac OS X or higher, and any Unix variant will continue to be acceptable.

4. The file output conventions are now compatible with PC^2, the automated online judging system used at the World Finals. (Sites are not required to use PC^2, but are encouraged to experiment with it. Four sites used it in 2004.) Input will still come from a file, but output must go to standard output (stdout, cout, or System.out), and debugging information may be written to standard error (stderr, cerr/clog, or System.err).

5. Until now, the Regional Chief Judges have tried their best to write problems that would not give teams a significant advantage based on their choice of language: C, C++, Java, or Pascal. (We dropped support for Pascal in 2004.) But C++ and Java are roughly comparable and provide vastly more functionality "out of the box" than C, due to their huge standard libraries. Therefore, C will continue to be fully supported, but the Regional Chief Judges will write problems with C++ and Java programmers in mind, and will only provide solutions in C++ or Java. It is possible that they may write problems that give C++ and Java programmers a significant advantage over C programmers.