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

class B:
    def __init__(self, txt: str):
        self.z: E = None
        self.s: A = None
        self.y: C = None
        self.q: G = None
        self.txt = txt

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

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

class E:
    def __init__(self, txt: str):
        self.t: F = None
        self.s: G = None
        self.o: G = None
        self.q: A = None
        self.v: C = None
        self.txt = txt

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

class G:
    def __init__(self, txt: str):
        self.t: A = None
        self.v: A = None
        self.u: F = None
        self.r: C = None
        self.q: C = None
        self.o: D = None
        self.p: D = None
        self.txt = txt

k = A("k")
h = B("h")
a = C("a")
b = D("b")
e = E("e")
i = F("i")
f = G("f")

k.w = e
k.t = e
k.v = h
h.z = e
h.s = k
h.y = a
h.q = f
a.w = b
a.p = h
a.r = f
a.o = f
a.s = i
a.t = e
b.w = e
b.z = f
b.o = f
b.t = h
b.v = h
b.q = a
e.t = i
e.s = f
e.o = f
e.q = k
e.v = a
i.p = b
i.u = e
i.o = e
f.t = k
f.v = k
f.u = i
f.r = a
f.q = a
f.o = b
f.p = b
assert f.v.t.t.u.v.t.s.txt == "
class A:
    def __init__(self, txt: str):
        self.w: E = None
        self.t: E = None
        self.v: B = None
        self.txt = txt

class B:
    def __init__(self, txt: str):
        self.z: E = None
        self.s: A = None
        self.y: C = None
        self.q: G = None
        self.txt = txt

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

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

class E:
    def __init__(self, txt: str):
        self.t: F = None
        self.s: G = None
        self.o: G = None
        self.q: A = None
        self.v: C = None
        self.txt = txt

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

class G:
    def __init__(self, txt: str):
        self.t: A = None
        self.v: A = None
        self.u: F = None
        self.r: C = None
        self.q: C = None
        self.o: D = None
        self.p: D = None
        self.txt = txt

k = A("k")
h = B("h")
a = C("a")
b = D("b")
e = E("e")
i = F("i")
f = G("f")

k.w = e
k.t = e
k.v = h
h.z = e
h.s = k
h.y = a
h.q = f
a.w = b
a.p = h
a.r = f
a.o = f
a.s = i
a.t = e
b.w = e
b.z = f
b.o = f
b.t = h
b.v = h
b.q = a
e.t = i
e.s = f
e.o = f
e.q = k
e.v = a
i.p = b
i.u = e
i.o = e
f.t = k
f.v = k
f.u = i
f.r = a
f.q = a
f.o = b
f.p = b
assert f.v.t.t.u.v.t.s.txt == "f"