How to call the return values from the classes below to the above class in python? [duplicate]

Question

I am trying to call the return values of a function within a class (Second) to another class(First) using super(). The class - Second is below class First. The code is as follows

class First(Second):
    def __init__(self):
        super().__init__()
        self.num1 = 1
    
    # add num
    def add_nums(self):
        print(self.num1 + self.set_num2()) 


class Second:
    def __init__(self):
        self.num2 = 2

    # Set num2
    def set_num2(self):
        return self.num2

a = First()
a.add_nums()

This actually works. However, if I add another class - Third below Second and call it in the class First, it doesn't work.

For instance, the following code doesn't work

class First(Second,Third):
    def __init__(self):
        super().__init__()
        self.num1 = 1
    
    # add num
    def add_nums(self):
        print(self.num1 + self.set_num2() + self.set_num3()) 


class Second:
    def __init__(self):
        self.num2 = 2

    # Set num
    def set_num2(self):
        return self.num2


class Third:
    def __init__(self):
        self.num3 = 3
    
    def set_num3(self):
        return self.num3

a = First()
a.add_nums()