Sets and Maps_Lab05_AverageStudentsGrades/

import java.util.*;

public class Lab05_AverageStudentsGrades {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        Map<String, List<Double>> students = new TreeMap<>();

        int numberOfStudents = Integer.parseInt(scanner.nextLine());

        for (int i = 0; i < numberOfStudents; i++) {
            String[] input = scanner.nextLine().split(" ");

            String name = input[0];
            double grade = Double.parseDouble(input[1]);

            students.putIfAbsent(name, new ArrayList<>());
            students.get(name).add(grade);
        }

        students.entrySet()
                .stream()
                .forEach(student -> {

                    System.out.printf("%s -> ", student.getKey());
                    student.getValue()
                            .stream()
                            .forEach(e -> System.out.printf("%.2f ", e));

                    double averageGrade = student.getValue().stream()
                            .mapToDouble(listElement -> listElement)
                            .average().getAsDouble();

                    System.out.printf("(avg: %.2f)%n", averageGrade);

                });


    }
}