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

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

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

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

class E:
    def __init__(self, txt: str):
        self.p: F = None
        self.r: F = None
        self.y: D = None
        self.txt = txt

class F:
    def __init__(self, txt: str):
        self.p: B = None
        self.x: E = None
        self.r: F = None
        self.o: B = None
        self.w: F = None
        self.u: E = None
        self.txt = txt

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

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

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

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

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

class E:
    def __init__(self, txt: str):
        self.p: F = None
        self.r: F = None
        self.y: D = None
        self.txt = txt

class F:
    def __init__(self, txt: str):
        self.p: B = None
        self.x: E = None
        self.r: F = None
        self.o: B = None
        self.w: F = None
        self.u: E = None
        self.txt = txt

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

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