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

class B:
    def __init__(self, txt: str):
        self.w: D = None
        self.u: F = None
        self.v: D = None
        self.o: D = None
        self.t: B = None
        self.txt = txt

class C:
    def __init__(self, txt: str):
        self.r: D = None
        self.v: E = None
        self.y: E = None
        self.x: F = None
        self.o: B = None
        self.u: D = None
        self.txt = txt

class D:
    def __init__(self, txt: str):
        self.p: B = None
        self.x: B = None
        self.txt = txt

class E:
    def __init__(self, txt: str):
        self.y: D = None
        self.q: B = None
        self.r: F = None
        self.u: C = None
        self.x: C = None
        self.t: A = None
        self.txt = txt

class F:
    def __init__(self, txt: str):
        self.x: A = None
        self.p: A = None
        self.v: E = None
        self.txt = txt

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

i.x = c
a.w = j
a.v = j
a.o = j
a.u = h
a.t = n
l.r = j
l.u = j
l.v = b
l.y = b
l.x = h
l.o = a
j.p = n
j.x = a
b.y = j
b.q = a
b.r = h
b.u = f
b.x = l
b.t = d
h.x = c
h.p = i
h.v = b
f.r = j
f.u = j
f.v = b
f.y = b
f.x = h
f.o = a
n.w = j
n.v = j
n.o = j
n.u = h
n.t = a
c.x = i
d.x = c
assert l.r.p.w.x.t.txt == "
class A:
    def __init__(self, txt: str):
        self.x: A = None
        self.txt = txt

class B:
    def __init__(self, txt: str):
        self.w: D = None
        self.u: F = None
        self.v: D = None
        self.o: D = None
        self.t: B = None
        self.txt = txt

class C:
    def __init__(self, txt: str):
        self.r: D = None
        self.v: E = None
        self.y: E = None
        self.x: F = None
        self.o: B = None
        self.u: D = None
        self.txt = txt

class D:
    def __init__(self, txt: str):
        self.p: B = None
        self.x: B = None
        self.txt = txt

class E:
    def __init__(self, txt: str):
        self.y: D = None
        self.q: B = None
        self.r: F = None
        self.u: C = None
        self.x: C = None
        self.t: A = None
        self.txt = txt

class F:
    def __init__(self, txt: str):
        self.x: A = None
        self.p: A = None
        self.v: E = None
        self.txt = txt

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

i.x = c
a.w = j
a.v = j
a.o = j
a.u = h
a.t = n
l.r = j
l.u = j
l.v = b
l.y = b
l.x = h
l.o = a
j.p = n
j.x = a
b.y = j
b.q = a
b.r = h
b.u = f
b.x = l
b.t = d
h.x = c
h.p = i
h.v = b
f.r = j
f.u = j
f.v = b
f.y = b
f.x = h
f.o = a
n.w = j
n.v = j
n.o = j
n.u = h
n.t = a
c.x = i
d.x = c
assert l.r.p.w.x.t.txt == "n"