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

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

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

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

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

class F:
    def __init__(self, txt: str):
        self.y: B = None
        self.txt = txt

j = A("j")
f = B("f")
d = C("d")
l = D("l")
n = E("n")
e = F("e")
b = D("b")

j.t = d
j.s = d
j.z = n
f.x = n
f.u = e
d.u = j
d.x = b
d.v = f
d.q = f
d.t = f
l.z = d
l.p = d
l.t = b
l.r = f
l.o = f
l.v = n
n.x = e
n.s = d
n.q = l
n.u = l
e.y = f
b.z = d
b.p = d
b.t = l
b.r = f
b.o = f
b.v = n
assert j.s.v.u.y.x.s.txt == "
class A:
    def __init__(self, txt: str):
        self.t: C = None
        self.z: E = None
        self.s: C = None
        self.txt = txt

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

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

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

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

class F:
    def __init__(self, txt: str):
        self.y: B = None
        self.txt = txt

j = A("j")
f = B("f")
d = C("d")
l = D("l")
n = E("n")
e = F("e")
b = D("b")

j.t = d
j.s = d
j.z = n
f.x = n
f.u = e
d.u = j
d.x = b
d.v = f
d.q = f
d.t = f
l.z = d
l.p = d
l.t = b
l.r = f
l.o = f
l.v = n
n.x = e
n.s = d
n.q = l
n.u = l
e.y = f
b.z = d
b.p = d
b.t = l
b.r = f
b.o = f
b.v = n
assert j.s.v.u.y.x.s.txt == "d"