class A:
    def __init__(self, txt: str):
        self.o: E = None
        self.s: B = None
        self.z: B = None
        self.v: B = None
        self.u: B = None
        self.q: B = None
        self.txt = txt

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

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

class D:
    def __init__(self, txt: str):
        self.p: C = None
        self.v: E = None
        self.o: F = None
        self.txt = txt

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

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

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

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

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

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

class D:
    def __init__(self, txt: str):
        self.p: C = None
        self.v: E = None
        self.o: F = None
        self.txt = txt

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

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

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

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