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

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

class C:
    def __init__(self, txt: str):
        self.w: D = None
        self.y: F = None
        self.s: F = None
        self.txt = txt

class D:
    def __init__(self, txt: str):
        self.o: B = None
        self.z: E = None
        self.txt = txt

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

class F:
    def __init__(self, txt: str):
        self.z: B = None
        self.y: B = None
        self.s: D = None
        self.q: E = None
        self.txt = txt

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

b.z = j
b.t = j
b.q = j
b.r = d
b.u = c
b.o = m
e.t = j
e.p = i
e.s = d
l.w = i
l.y = c
l.s = c
i.o = e
i.z = j
j.q = i
j.t = i
c.z = e
c.y = e
c.s = i
c.q = j
m.w = i
m.y = c
m.s = c
d.z = e
d.y = e
d.s = i
d.q = j
assert d.y.p.o.p.o.s.s.txt == "
class A:
    def __init__(self, txt: str):
        self.z: E = None
        self.r: F = None
        self.t: E = None
        self.q: E = None
        self.u: F = None
        self.o: C = None
        self.txt = txt

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

class C:
    def __init__(self, txt: str):
        self.w: D = None
        self.y: F = None
        self.s: F = None
        self.txt = txt

class D:
    def __init__(self, txt: str):
        self.o: B = None
        self.z: E = None
        self.txt = txt

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

class F:
    def __init__(self, txt: str):
        self.z: B = None
        self.y: B = None
        self.s: D = None
        self.q: E = None
        self.txt = txt

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

b.z = j
b.t = j
b.q = j
b.r = d
b.u = c
b.o = m
e.t = j
e.p = i
e.s = d
l.w = i
l.y = c
l.s = c
i.o = e
i.z = j
j.q = i
j.t = i
c.z = e
c.y = e
c.s = i
c.q = j
m.w = i
m.y = c
m.s = c
d.z = e
d.y = e
d.s = i
d.q = j
assert d.y.p.o.p.o.s.s.txt == "i"