Download the .jar. Then make a folder called res in the same location as the current location of the .jar.
Download input.txt and place it in the res-folder. Supported Arithmetic and Notation can be found in input.txt.
Run the .jar, and a new output file, output.txt, will be created in the res-folder.
In case the res-folder does not exist, the .jar will create one. If input.txt does not exist, no computations will be made (and output.txt will not be created). If there already exists a file called output.txt, it'll be overwritten!