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

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

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

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

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

class F:
    def __init__(self, txt: str):
        self.t: A = None
        self.y: D = None
        self.q: B = None
        self.u: D = None
        self.txt = txt

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

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

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

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

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

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

class F:
    def __init__(self, txt: str):
        self.t: A = None
        self.y: D = None
        self.q: B = None
        self.u: D = None
        self.txt = txt

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

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