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

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

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

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

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

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

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

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

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

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

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

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

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

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

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