Rita is writing a c++ programe in whic, she wants to display the grades (stored in variable grade) as per the table of marks (stored in variable marks) given below: a – 90-100 b – 80-89 c – 70-79 d < 70

#include <iostream>
#include <vector>
using namespace std;

class Student
{
public:   
    Student(int mark)   
    {        
        this->mark = mark;

        if (mark >= 90 && mark <= 100)
            grade = 'A';
        else if (mark >= 80 && mark <= 89)            
            grade = 'B';
        else if (mark >= 70 && mark <= 79)
            grade = 'C';
        else if (mark < 70 && mark >= 0)
            grade = 'D';
        else
            cout << "Invalid mark, grade not assigned";
    }

    int getMark()
    {
        return mark;
    }

    char getGrade()
    {
        return grade;
    }

private:
    int mark;
    char grade;
};

int main()
{
    vector<Student> students;
    int num, mark;

    cout << "Enter number of students: ";
    cin >> num;

    if (num <= 0)
        cout << "Invalid number of students, exiting";
    else
    {
        for (int i = 1; i <= num; i++)
        {
            cout << "Enter marks for student " << i << ": ";
            cin >> mark;

            Student s(mark);
            students.push_back(s);
        }
    }

    // do whatever you like with the vector from here onwards, such as:
    /*
    for (int i = 0; i < students.size(); i++)
    {
        cout << "Student " << i + 1 << " grade: " << students[i].getGrade() << endl;
    }
    */

    return 0;
}