class A:
    def __init__(self, txt: str):
        self.w: E = None
        self.u: F = None
        self.p: F = None
        self.txt = txt

class B:
    def __init__(self, txt: str):
        self.y: D = None
        self.txt = txt

class C:
    def __init__(self, txt: str):
        self.t: B = None
        self.v: F = None
        self.r: E = None
        self.o: B = None
        self.txt = txt

class D:
    def __init__(self, txt: str):
        self.y: E = None
        self.p: F = None
        self.x: C = None
        self.v: C = None
        self.w: A = None
        self.z: E = None
        self.txt = txt

class E:
    def __init__(self, txt: str):
        self.v: F = None
        self.o: C = None
        self.y: B = None
        self.t: F = None
        self.w: D = None
        self.r: D = None
        self.txt = txt

class F:
    def __init__(self, txt: str):
        self.v: E = None
        self.txt = txt

e = A("e")
i = B("i")
c = C("c")
d = D("d")
n = E("n")
b = F("b")

e.w = n
e.u = b
e.p = b
i.y = d
c.t = i
c.o = i
c.v = b
c.r = n
d.y = n
d.z = n
d.p = b
d.x = c
d.v = c
d.w = e
n.v = b
n.t = b
n.o = c
n.y = i
n.w = d
n.r = d
b.v = n
assert c.v.v.y.txt == "
class A:
    def __init__(self, txt: str):
        self.w: E = None
        self.u: F = None
        self.p: F = None
        self.txt = txt

class B:
    def __init__(self, txt: str):
        self.y: D = None
        self.txt = txt

class C:
    def __init__(self, txt: str):
        self.t: B = None
        self.v: F = None
        self.r: E = None
        self.o: B = None
        self.txt = txt

class D:
    def __init__(self, txt: str):
        self.y: E = None
        self.p: F = None
        self.x: C = None
        self.v: C = None
        self.w: A = None
        self.z: E = None
        self.txt = txt

class E:
    def __init__(self, txt: str):
        self.v: F = None
        self.o: C = None
        self.y: B = None
        self.t: F = None
        self.w: D = None
        self.r: D = None
        self.txt = txt

class F:
    def __init__(self, txt: str):
        self.v: E = None
        self.txt = txt

e = A("e")
i = B("i")
c = C("c")
d = D("d")
n = E("n")
b = F("b")

e.w = n
e.u = b
e.p = b
i.y = d
c.t = i
c.o = i
c.v = b
c.r = n
d.y = n
d.z = n
d.p = b
d.x = c
d.v = c
d.w = e
n.v = b
n.t = b
n.o = c
n.y = i
n.w = d
n.r = d
b.v = n
assert c.v.v.y.txt == "i"