shazain07/mern-day4 ? reverse-engineered prompt

Build me a simple Node.js and Express REST API for a Student Management System.

I want full CRUD for students, with these routes: get all students, get one student by ID, create a student, update a student, and delete a student. Each student should have an id, name, email, course, and marks, and the data can be stored in memory for now.

Please add basic validation so the app returns a clear error if required fields are missing or if someone uses a bad ID. Use clean JSON responses with a success flag, helpful messages, and proper HTTP status codes like 200, 201, 400, and 404. Also make the error handling feel polished and consistent.

Set it up so I can run it locally on port 5000 with a dev command, and include a few sample student records so the API works right away. If you need to check current docs online for anything, go ahead and do that.