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

class B:
    def __init__(self, txt: str):
        self.p: C = None
        self.z: E = None
        self.w: F = None
        self.v: C = None
        self.q: E = None
        self.txt = txt

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

class D:
    def __init__(self, txt: str):
        self.z: B = None
        self.w: E = None
        self.y: B = None
        self.u: D = None
        self.q: A = None
        self.txt = txt

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

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

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

b.y = n
k.p = i
k.z = a
k.w = c
k.v = f
k.q = d
f.w = c
f.u = b
f.p = d
j.z = k
j.y = k
j.w = d
j.u = e
j.q = b
a.z = n
a.o = c
c.s = b
c.w = f
c.p = n
d.z = n
d.o = c
i.w = c
i.u = b
i.p = n
n.z = a
n.o = c
e.z = k
e.y = k
e.w = n
e.u = j
e.q = b
assert k.v.u.y.z.o.txt == "
class A:
    def __init__(self, txt: str):
        self.y: E = None
        self.txt = txt

class B:
    def __init__(self, txt: str):
        self.p: C = None
        self.z: E = None
        self.w: F = None
        self.v: C = None
        self.q: E = None
        self.txt = txt

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

class D:
    def __init__(self, txt: str):
        self.z: B = None
        self.w: E = None
        self.y: B = None
        self.u: D = None
        self.q: A = None
        self.txt = txt

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

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

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

b.y = n
k.p = i
k.z = a
k.w = c
k.v = f
k.q = d
f.w = c
f.u = b
f.p = d
j.z = k
j.y = k
j.w = d
j.u = e
j.q = b
a.z = n
a.o = c
c.s = b
c.w = f
c.p = n
d.z = n
d.o = c
i.w = c
i.u = b
i.p = n
n.z = a
n.o = c
e.z = k
e.y = k
e.w = n
e.u = j
e.q = b
assert k.v.u.y.z.o.txt == "c"