this is JetBrains Intellij Idea project. To run it, open .iml-file with this IDE -> add new application configuration -> add Main class -> run.
If you prefer terminal:
javac -classpath ./out -d ./out src/ex1Labyrinth.java
javac -classpath ./out -d ./out src/CalculateExpression.java
javac -classpath ./out -d ./out src/Main.java
java -classpath ./out Main
see task5-5/readme.md for details