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

class B:
    def __init__(self, txt: str):
        self.u: H = None
        self.o: F = None
        self.r: G = None
        self.txt = txt

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

class D:
    def __init__(self, txt: str):
        self.q: C = None
        self.r: H = None
        self.w: F = None
        self.t: F = None
        self.txt = txt

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

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

class G:
    def __init__(self, txt: str):
        self.z: E = None
        self.txt = txt

class H:
    def __init__(self, txt: str):
        self.t: E = None
        self.u: A = None
        self.z: C = None
        self.o: E = None
        self.q: B = None
        self.v: D = None
        self.r: A = None
        self.txt = txt

class I:
    def __init__(self, txt: str):
        self.t: E = None
        self.x: H = None
        self.txt = txt

class J:
    def __init__(self, txt: str):
        self.y: H = None
        self.q: I = None
        self.txt = txt

e = A("e")
l = B("l")
a = C("a")
n = D("n")
d = E("d")
f = F("f")
b = G("b")
m = H("m")
j = I("j")
k = J("k")

e.y = a
e.z = m
e.v = m
e.w = l
l.u = m
l.o = f
l.r = b
a.y = d
a.o = f
n.q = a
n.r = m
n.w = f
n.t = f
d.r = f
d.u = a
f.y = d
f.s = a
b.z = d
m.t = d
m.o = d
m.u = e
m.r = e
m.z = a
m.q = l
m.v = n
j.t = d
j.x = m
k.y = m
k.q = j
assert d.u.o.s.y.u.o.y.r.txt == "
class A:
    def __init__(self, txt: str):
        self.y: C = None
        self.z: H = None
        self.w: B = None
        self.v: H = None
        self.txt = txt

class B:
    def __init__(self, txt: str):
        self.u: H = None
        self.o: F = None
        self.r: G = None
        self.txt = txt

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

class D:
    def __init__(self, txt: str):
        self.q: C = None
        self.r: H = None
        self.w: F = None
        self.t: F = None
        self.txt = txt

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

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

class G:
    def __init__(self, txt: str):
        self.z: E = None
        self.txt = txt

class H:
    def __init__(self, txt: str):
        self.t: E = None
        self.u: A = None
        self.z: C = None
        self.o: E = None
        self.q: B = None
        self.v: D = None
        self.r: A = None
        self.txt = txt

class I:
    def __init__(self, txt: str):
        self.t: E = None
        self.x: H = None
        self.txt = txt

class J:
    def __init__(self, txt: str):
        self.y: H = None
        self.q: I = None
        self.txt = txt

e = A("e")
l = B("l")
a = C("a")
n = D("n")
d = E("d")
f = F("f")
b = G("b")
m = H("m")
j = I("j")
k = J("k")

e.y = a
e.z = m
e.v = m
e.w = l
l.u = m
l.o = f
l.r = b
a.y = d
a.o = f
n.q = a
n.r = m
n.w = f
n.t = f
d.r = f
d.u = a
f.y = d
f.s = a
b.z = d
m.t = d
m.o = d
m.u = e
m.r = e
m.z = a
m.q = l
m.v = n
j.t = d
j.x = m
k.y = m
k.q = j
assert d.u.o.s.y.u.o.y.r.txt == "f"