Student grade Calculation Scanner Using Java

Input the Student Indexno,Name,subjects in java

1. Display the Student details
2. Display the the max marks
3. Display the total,average and grade
4. Exit

Please select one option

import java.util.Scanner;

public class Student {
    public void Main(String args[])
    {

        Scanner scan = new Scanner(System.in);

        System.out.print("Enter Student Index No : ");
        String IndexNo = scan.next();

        System.out.print("Enter Student Name : ");
        String name = scan.next();

        System.out.print("Enter Number of Subjects : ");
        int number_of_subjects = scan.nextInt();
        System.out.println();

        int marks = 0;
        int max = 0;
        int tot = 0;

        for (int a = 0; a < number_of_subjects; a++)
        {
            System.out.print("Enter Subject " + (a + 1) + " Marks : ");
            marks = scan.nextInt();
            if (max < marks) {
                max = marks;
            }
            tot = tot + marks;
        }

        boolean b = true;
        while (b) {
            System.out.println();
            System.out.println("A. Display Student Details.");
            System.out.println("B. Display Maximum Marks.");
            System.out.println("C. Display Total, Average & Result.");
            System.out.println("X. Exit.");
            System.out.println();
            System.out.print("select one option Here : ");
            String option = scan.next();
            System.out.println();
            switch (option) {
                case "A":
                    System.out.println("Student IndexNo : " + IndexNo);
                    System.out.println("Student Name : " + name);

                    break;
                case "B":
                    System.out.println("Maximum Marks : " + max);
                    break;
                case "C":
                    double avg = tot / (double) number_of_subjects;
                    String grade = "Fail";
                    if (avg >= 50) {
                        grade = "Pass";
                    }
                    System.out.println("Your Total : " + tot);
                    System.out.println(" Your Average : " + avg);
                    System.out.println("Your Grade : " + grade);
                    break;
                case "X":
                    System.out.println("Exit");
                    b = false;
                    break;
                default:
                    System.out.println("Please select valid option.");
            }
        }
    }
}

i have attached the video link below. which will do this tutorials step by step