import java.util.*;

public class HashStudents {

public static void main(String[] args) {

HashMap<String, List<String>> h1 = new LinkedHashMap<>();

HashMap<String, String> h2 = new LinkedHashMap<>();

// Check if HashMap is empty

System.out.println("is studentsMapping empty?: " + h1.isEmpty());

System.out.println("is studentsMapping empty?: " + h2.isEmpty());

// creating list of subjects and adding to hash map

List<String> subjects = Arrays.asList("Python", "Math", "C");

h1.put("A", subjects);

subjects = Arrays.asList("C", "C++");

h1.put("B", subjects);

subjects = Arrays.asList("C++", "Physics", "Chemistry");

h1.put("C", subjects);

// creating hashmap of faculty

h2.put("Python", "111");

h2.put("Math", "222");

h2.put("C", "333");

h2.put("C++", "444");

// displaying all students and subjects

for (Map.Entry m : h1.entrySet()) {

System.out.println(m.getKey() + " " + m.getValue());

}

// displaying all subjects and faculty

for (Map.Entry m : h2.entrySet()) {

System.out.println(m.getKey() + " " + m.getValue());

}

Scanner sc = new Scanner(System.in);

System.out.print("Enter a student: ");

String s = sc.nextLine();

System.out.println("Faculties are: ");

h1.forEach((k, v) -> {

if (k.equals(s))

v.forEach(w -> {

for (Map.Entry m : h2.entrySet()) {

if (m.getKey().equals(w))

System.out.println(m.getValue());

}

});

});

}

}