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

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

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

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

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

class F:
    def __init__(self, txt: str):
        self.q: C = None
        self.p: B = None
        self.y: E = None
        self.o: C = None
        self.txt = txt

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

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

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

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

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

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

class F:
    def __init__(self, txt: str):
        self.q: C = None
        self.p: B = None
        self.y: E = None
        self.o: C = None
        self.txt = txt

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

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