class A:
def f(self):
print("A", end="")
class B(A):
def f(self):
print("B", end="")
super().f()
A.f(self)
class C(A):
def f(self):
print("C", end="")
super().f()
A.f(self)
class D(B, C):
def f(self):
print("D", end="")
super().f()
d = D()
d.f()