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

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

class C:
    def __init__(self, txt: str):
        self.r: F = None
        self.z: B = None
        self.s: A = None
        self.txt = txt

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

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

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

b = A("b")
g = B("g")
h = C("h")
c = D("c")
l = E("l")
a = F("a")
n = A("n")
j = E("j")
d = E("d")
k = C("k")

b.w = d
b.u = a
b.z = h
b.t = g
g.s = a
g.w = c
h.r = a
h.z = g
h.s = n
c.x = g
c.t = g
c.s = j
l.y = c
l.z = c
l.w = k
l.t = n
a.o = l
a.v = d
n.w = j
n.u = a
n.z = h
n.t = g
j.y = c
j.z = c
j.w = k
j.t = n
d.y = c
d.z = c
d.w = h
d.t = b
k.r = a
k.z = g
k.s = n
assert d.z.s.z.x.s.v.w.r.v.y.txt == "
class A:
    def __init__(self, txt: str):
        self.w: E = None
        self.u: F = None
        self.z: C = None
        self.t: B = None
        self.txt = txt

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

class C:
    def __init__(self, txt: str):
        self.r: F = None
        self.z: B = None
        self.s: A = None
        self.txt = txt

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

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

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

b = A("b")
g = B("g")
h = C("h")
c = D("c")
l = E("l")
a = F("a")
n = A("n")
j = E("j")
d = E("d")
k = C("k")

b.w = d
b.u = a
b.z = h
b.t = g
g.s = a
g.w = c
h.r = a
h.z = g
h.s = n
c.x = g
c.t = g
c.s = j
l.y = c
l.z = c
l.w = k
l.t = n
a.o = l
a.v = d
n.w = j
n.u = a
n.z = h
n.t = g
j.y = c
j.z = c
j.w = k
j.t = n
d.y = c
d.z = c
d.w = h
d.t = b
k.r = a
k.z = g
k.s = n
assert d.z.s.z.x.s.v.w.r.v.y.txt == "c"