//Zadanie3
                Dataset<Row> department = spark.read().option("header", "true").csv("departments.csv");
                Dataset<Row> products = spark.read().option("header", "true").csv("products.csv");
                Dataset<Row> products_department = products.join(department, "department_id");
                Dataset<Row> pdCtr = products_department.groupBy("department").count();

                Dataset<Row> all = pdCtr.select(pdCtr.col("department"), pdCtr.col("count"), pdCtr.col("count").divide(products.count()).multiply(100).as("precent"));
                all.show();