class A:
    def __init__(self, txt: str):
        self.y: D = None
        self.z: C = None
        self.v: F = None
        self.p: D = None
        self.t: C = None
        self.txt = txt

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

class C:
    def __init__(self, txt: str):
        self.z: E = None
        self.w: E = None
        self.txt = txt

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

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

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

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

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

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

class C:
    def __init__(self, txt: str):
        self.z: E = None
        self.w: E = None
        self.txt = txt

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

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

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

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

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