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

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

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

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

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

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

c = A("c")
a = B("a")
h = C("h")
d = D("d")
l = E("l")
m = F("m")
k = C("k")
n = F("n")
i = A("i")
f = F("f")

c.z = d
c.w = d
c.u = d
c.t = n
a.s = f
a.w = h
a.v = l
h.y = c
h.r = l
h.t = l
h.v = i
h.x = k
d.o = l
d.s = a
l.v = a
l.w = a
l.z = k
m.y = h
m.q = d
m.o = d
m.s = c
m.u = c
k.y = c
k.v = c
k.r = l
k.t = l
k.x = h
n.y = h
n.q = d
n.o = d
n.s = c
n.u = i
i.z = d
i.w = d
i.u = d
i.t = f
f.y = k
f.q = d
f.o = d
f.s = i
f.u = c
assert k.y.u.s.s.s.t.q.s.txt == "
class A:
    def __init__(self, txt: str):
        self.z: D = None
        self.w: D = None
        self.u: D = None
        self.t: F = None
        self.txt = txt

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

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

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

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

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

c = A("c")
a = B("a")
h = C("h")
d = D("d")
l = E("l")
m = F("m")
k = C("k")
n = F("n")
i = A("i")
f = F("f")

c.z = d
c.w = d
c.u = d
c.t = n
a.s = f
a.w = h
a.v = l
h.y = c
h.r = l
h.t = l
h.v = i
h.x = k
d.o = l
d.s = a
l.v = a
l.w = a
l.z = k
m.y = h
m.q = d
m.o = d
m.s = c
m.u = c
k.y = c
k.v = c
k.r = l
k.t = l
k.x = h
n.y = h
n.q = d
n.o = d
n.s = c
n.u = i
i.z = d
i.w = d
i.u = d
i.t = f
f.y = k
f.q = d
f.o = d
f.s = i
f.u = c
assert k.y.u.s.s.s.t.q.s.txt == "a"