college hierarchy

#include <iostream>
using namespace std;

class College
{
protected:
    string collegeName;
    int collegeCode;

public:
    College(void)
    {
        cout << "Enter the details below:\n";
        cout << "Enter the college Name: ";
        cin >> collegeName;
        cout << "Enter the college code: ";
        cin >> collegeCode;
    }
};

class Department : public College
{
protected:
    string Dept;

public:
    int a;
    Department(void)
    {
        cout << "Select the Department:\n1--> Mechanical Department.\n2--> Electrical Department\n3--> Civil Department\n4--> CSE Department\n";
        cin >> a;
        switch (a)
        {
        case 1:
            Dept = "Mechanical Department";
            break;
        case 2:
            Dept = "Electrical Department";
            break;
        case 3:
            Dept = "Civil Department";
            break;
        case 4:
            Dept = "CSE Department";
            break;
        default:
            Dept = "Invalid";
            cout << "Please choose correct option";
            break;
        }
    }
};

class Staff : public Department
{
protected:
    string staffName;
    string task;
    int age;

public:
    Staff(void)
    {
        cout << "\n\n\nEnter the Staff Name: ";
        cin >> staffName;
        cout << "\nEnter the Staff's task (Teaching Subject): ";
        cin >> task;
        cout << "\nEnter the Staff's Age: ";
        cin >> age;
    }
    void display(){
        cout<<"\n\nStaff Details:\n"
            <<"College Name : "<<collegeName<<endl
            <<"College Code: "<<collegeCode<<endl
            <<"Department: "<<Dept<<endl
            <<"Age: "<<age<<endl
            <<"Staff Name: "<<staffName<<endl
            <<"Teaching Subject: "<<task<<endl;
    }
};

class Student : public Department
{
protected:
    string studentName;
    int age, rollNo;

public:
    Student(void)
    {
        cout << "\n\n\nEnter the Student Name: ";
        cin >> studentName;
        cout << "\nEnter the Students's Age: ";
        cin >> age;
        cout << "\nEnter the Student's Roll No.: ";
        cin >> rollNo;
    }
    void display(){
        cout<<"\n\nStudent Details:\n"
            <<"College Name : "<<collegeName<<endl
            <<"College Code: "<<collegeCode<<endl
            <<"Department: "<<Dept<<endl
            <<"Age: "<<age<<endl
            <<"Student Name: "<<studentName<<endl
            <<"Roll No.: "<<rollNo<<endl;
    }
};

int main()
{
    Student s1;
    s1.display();
    Staff s2;
    s2.display();
    return 0;
}