class A:
    def __init__(self, txt: str):
        self.v: B = None
        self.y: C = None
        self.s: B = None
        self.x: B = None
        self.txt = txt

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

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

class D:
    def __init__(self, txt: str):
        self.w: A = None
        self.o: A = None
        self.s: C = None
        self.txt = txt

i = A("i")
e = B("e")
a = C("a")
h = D("h")
d = C("d")
n = B("n")
l = B("l")
k = D("k")
g = D("g")

i.v = n
i.y = a
i.s = l
i.x = e
e.r = i
e.t = i
e.w = k
e.u = k
a.r = g
a.o = i
a.u = d
h.w = i
h.o = i
h.s = d
d.r = g
d.o = i
d.u = a
n.r = i
n.t = i
n.w = g
n.u = k
l.r = i
l.t = i
l.w = k
l.u = g
k.w = i
k.o = i
k.s = a
g.w = i
g.o = i
g.s = d
assert e.t.s.u.s.u.txt == "
class A:
    def __init__(self, txt: str):
        self.v: B = None
        self.y: C = None
        self.s: B = None
        self.x: B = None
        self.txt = txt

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

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

class D:
    def __init__(self, txt: str):
        self.w: A = None
        self.o: A = None
        self.s: C = None
        self.txt = txt

i = A("i")
e = B("e")
a = C("a")
h = D("h")
d = C("d")
n = B("n")
l = B("l")
k = D("k")
g = D("g")

i.v = n
i.y = a
i.s = l
i.x = e
e.r = i
e.t = i
e.w = k
e.u = k
a.r = g
a.o = i
a.u = d
h.w = i
h.o = i
h.s = d
d.r = g
d.o = i
d.u = a
n.r = i
n.t = i
n.w = g
n.u = k
l.r = i
l.t = i
l.w = k
l.u = g
k.w = i
k.o = i
k.s = a
g.w = i
g.o = i
g.s = d
assert e.t.s.u.s.u.txt == "a"