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

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

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

class D:
    def __init__(self, txt: str):
        self.q: C = None
        self.w: A = None
        self.t: B = None
        self.p: C = None
        self.v: B = None
        self.o: B = None
        self.txt = txt

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

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

e = A("e")
i = B("i")
j = C("j")
a = D("a")
k = E("k")
c = F("c")

e.v = a
e.s = a
e.w = j
e.o = j
e.r = k
e.p = i
i.v = e
i.y = e
i.x = e
i.p = k
i.t = c
i.u = a
j.s = a
j.v = k
j.r = k
j.u = c
a.q = j
a.p = j
a.w = e
a.t = i
a.v = i
a.o = i
k.y = c
c.u = k
assert i.y.r.y.u.y.u.txt == "
class A:
    def __init__(self, txt: str):
        self.v: D = None
        self.w: C = None
        self.s: D = None
        self.r: E = None
        self.p: B = None
        self.o: C = None
        self.txt = txt

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

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

class D:
    def __init__(self, txt: str):
        self.q: C = None
        self.w: A = None
        self.t: B = None
        self.p: C = None
        self.v: B = None
        self.o: B = None
        self.txt = txt

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

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

e = A("e")
i = B("i")
j = C("j")
a = D("a")
k = E("k")
c = F("c")

e.v = a
e.s = a
e.w = j
e.o = j
e.r = k
e.p = i
i.v = e
i.y = e
i.x = e
i.p = k
i.t = c
i.u = a
j.s = a
j.v = k
j.r = k
j.u = c
a.q = j
a.p = j
a.w = e
a.t = i
a.v = i
a.o = i
k.y = c
c.u = k
assert i.y.r.y.u.y.u.txt == "k"