class A:
    def __init__(self, txt: str):
        self.t: C = None
        self.r: C = None
        self.u: A = None
        self.txt = txt

class B:
    def __init__(self, txt: str):
        self.o: A = None
        self.txt = txt

class C:
    def __init__(self, txt: str):
        self.u: B = None
        self.t: C = None
        self.y: A = None
        self.txt = txt

e = A("e")
i = B("i")
k = C("k")
a = A("a")
l = B("l")
j = C("j")
n = C("n")

e.t = n
e.r = j
e.u = a
i.o = a
k.u = l
k.t = j
k.y = e
a.t = n
a.r = j
a.u = e
l.o = a
j.u = l
j.t = k
j.y = e
n.u = l
n.t = k
n.y = a
assert e.u.r.u.txt == "
class A:
    def __init__(self, txt: str):
        self.t: C = None
        self.r: C = None
        self.u: A = None
        self.txt = txt

class B:
    def __init__(self, txt: str):
        self.o: A = None
        self.txt = txt

class C:
    def __init__(self, txt: str):
        self.u: B = None
        self.t: C = None
        self.y: A = None
        self.txt = txt

e = A("e")
i = B("i")
k = C("k")
a = A("a")
l = B("l")
j = C("j")
n = C("n")

e.t = n
e.r = j
e.u = a
i.o = a
k.u = l
k.t = j
k.y = e
a.t = n
a.r = j
a.u = e
l.o = a
j.u = l
j.t = k
j.y = e
n.u = l
n.t = k
n.y = a
assert e.u.r.u.txt == "l"