class MyClass:
instance_ref = []
def __init__(self):
MyClass.instance_ref.append(self)
a = MyClass()
b = MyClass()
c = MyClass()
d = MyClass()
a.weight = 3
b.weight = 4
c.weight = 5
d.weight = 6
add = sum([x.weight for x in MyClass.instance_ref])
print(add)
maximum = max([x.weight for x in MyClass.instance_ref])
print(maximum)