Why does this give me an error when using Inheritance - c++

Question

I am currently learning Inheritance. The code below works just fine.
#include <iostream>
class Student {
protected:
double GPA = 3.12;
};
class Employee {
protected:
int Salary = 1500;
};
class TeachingAssistant: public Student, public Employee {
public:
void Print() {
std::cout << GPA << " " << Salary << "\n";
}
};
int main() {
TeachingAssistant TA;
TA.Print();
}
However this code below does NOT work.
#include <iostream>
class Student {
protected:
double GPA = 3.12;
};
class Employee: public Student {
protected:
int Salary = 1500;
};
class TeachingAssistant: public Student, public Employee {
public:
void Print() {
std::cout << GPA << " " << Salary << "\n";
}
};
int main() {
TeachingAssistant TA;
TA.Print();
}
The Error
I only changed one thing in between these two code snippets and it's the addition of "public Student" next to the class Employee. What did I do wrong? Please explain this using simple words/logic.

Answer 1

Field GPA can be accessed from class TeachingAssistant by two ways:
TeachingAssistant -> Student
TeachingAssistant -> Employee -> Student
You must specify which one you need
For example:
std::cout << Employee::GPA << " " << Salary << "\n";
Another solution is to remove the other inheritance of class Student:
class TeachingAssistant: public Employee {
public:
void Print() {
std::cout << GPA << " " << Salary << "\n";
}
};

Answer 2

Your situation is the following: you have a teaching assistant who's an Student (1) and Employee (2) - however the Employee based on your design is also a student. You end up by having teaching assistant being two students and one employee. C++ is telling which student's you want me to print the GPA for, hence the ambiguous.
The design is simply wrong in the second code snippet.
TeachingAssistant is both an Employee and a Student: Yes.
An
Employee is a Student: No.