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

class B:
    def __init__(self, txt: str):
        self.y: A = None
        self.txt = txt

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

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

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

class F:
    def __init__(self, txt: str):
        self.x: C = None
        self.w: F = None
        self.y: C = None
        self.r: C = None
        self.txt = txt

c = A("c")
h = B("h")
i = C("i")
l = D("l")
k = E("k")
f = F("f")
e = D("e")
n = F("n")
g = B("g")

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

class B:
    def __init__(self, txt: str):
        self.y: A = None
        self.txt = txt

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

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

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

class F:
    def __init__(self, txt: str):
        self.x: C = None
        self.w: F = None
        self.y: C = None
        self.r: C = None
        self.txt = txt

c = A("c")
h = B("h")
i = C("i")
l = D("l")
k = E("k")
f = F("f")
e = D("e")
n = F("n")
g = B("g")

c.z = i
c.r = i
c.s = f
c.y = e
c.t = e
h.y = c
i.o = h
i.w = e
i.s = f
l.w = c
l.v = k
k.y = c
k.s = l
k.u = n
k.w = g
f.x = i
f.y = i
f.r = i
f.w = n
e.w = c
e.v = k
n.x = i
n.y = i
n.r = i
n.w = f
g.y = c
assert l.v.w.y.y.v.y.r.w.v.txt == "k"