class A:
    def __init__(self, txt: str):
        self.w: F = None
        self.z: E = None
        self.t: E = None
        self.v: F = None
        self.txt = txt

class B:
    def __init__(self, txt: str):
        self.s: A = None
        self.x: D = None
        self.y: E = None
        self.w: E = None
        self.v: C = None
        self.txt = txt

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

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

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

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

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

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

class B:
    def __init__(self, txt: str):
        self.s: A = None
        self.x: D = None
        self.y: E = None
        self.w: E = None
        self.v: C = None
        self.txt = txt

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

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

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

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

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

a.w = b
a.v = b
a.z = l
a.t = l
j.s = a
j.x = m
j.y = l
j.w = l
j.v = d
d.q = a
d.t = j
i.y = a
i.z = b
i.t = l
i.v = j
l.p = d
l.v = j
b.u = d
b.s = d
b.v = d
b.x = a
b.q = a
b.w = l
f.y = a
f.z = b
f.t = l
f.v = j
c.y = a
c.z = b
c.t = l
c.v = j
m.y = a
m.z = b
m.t = l
m.v = j
assert l.v.s.v.txt == "b"