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

class B:
    def __init__(self, txt: str):
        self.s: E = None
        self.txt = txt

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

class D:
    def __init__(self, txt: str):
        self.w: E = None
        self.v: C = None
        self.r: E = None
        self.u: C = None
        self.s: E = None
        self.p: B = None
        self.txt = txt

class E:
    def __init__(self, txt: str):
        self.s: A = None
        self.o: A = None
        self.x: F = None
        self.w: B = None
        self.txt = txt

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

l = A("l")
i = B("i")
n = C("n")
j = D("j")
m = E("m")
e = F("e")
d = B("d")
k = D("k")
a = C("a")

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

class B:
    def __init__(self, txt: str):
        self.s: E = None
        self.txt = txt

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

class D:
    def __init__(self, txt: str):
        self.w: E = None
        self.v: C = None
        self.r: E = None
        self.u: C = None
        self.s: E = None
        self.p: B = None
        self.txt = txt

class E:
    def __init__(self, txt: str):
        self.s: A = None
        self.o: A = None
        self.x: F = None
        self.w: B = None
        self.txt = txt

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

l = A("l")
i = B("i")
n = C("n")
j = D("j")
m = E("m")
e = F("e")
d = B("d")
k = D("k")
a = C("a")

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