student_management_system.py

class StudentManagementSystem:
    def __init__(self):
        self.students = {}

    def add_student(self, roll_number, name, age, grade):
        if roll_number not in self.students:
            self.students[roll_number] = {'name': name, 'age': age, 'grade': grade}
            print(f"Student with Roll Number {roll_number} added successfully.")
        else:
            print(f"Student with Roll Number {roll_number} already exists.")

    def display_student(self, roll_number):
        if roll_number in self.students:
            student_info = self.students[roll_number]
            print(f"Roll Number: {roll_number}")
            print(f"Name: {student_info['name']}")
            print(f"Age: {student_info['age']}")
            print(f"Grade: {student_info['grade']}")
        else:
            print(f"Student with Roll Number {roll_number} not found.")

    def display_all_students(self):
        if not self.students:
            print("No students in the system.")
        else:
            print("Student List:")
            for roll_number, student_info in self.students.items():
                print(f"Roll Number: {roll_number}, Name: {student_info['name']}, Age: {student_info['age']}, Grade: {student_info['grade']}")

    def remove_student(self, roll_number):
        if roll_number in self.students:
            del self.students[roll_number]
            print(f"Student with Roll Number {roll_number} removed successfully.")
        else:
            print(f"Student with Roll Number {roll_number} not found.")

# Example Usage:
if __name__ == "__main__":
    sms = StudentManagementSystem()

    sms.add_student(101, 'John Doe', 18, 'A')
    sms.add_student(102, 'Jane Doe', 17, 'B')

    sms.display_all_students()

    sms.display_student(101)

    sms.remove_student(102)

    sms.display_all_students()