class A:
    def __init__(self, txt: str):
        self.o: F = None
        self.x: J = None
        self.txt = txt

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

class C:
    def __init__(self, txt: str):
        self.v: J = None
        self.o: D = None
        self.txt = txt

class D:
    def __init__(self, txt: str):
        self.s: G = None
        self.txt = txt

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

class F:
    def __init__(self, txt: str):
        self.u: A = None
        self.x: E = None
        self.t: I = None
        self.o: C = None
        self.q: J = None
        self.txt = txt

class G:
    def __init__(self, txt: str):
        self.y: E = None
        self.p: D = None
        self.txt = txt

class H:
    def __init__(self, txt: str):
        self.t: F = None
        self.txt = txt

class I:
    def __init__(self, txt: str):
        self.x: B = None
        self.v: E = None
        self.q: G = None
        self.s: J = None
        self.o: C = None
        self.r: E = None
        self.u: A = None
        self.t: E = None
        self.z: C = None
        self.y: H = None
        self.txt = txt

class J:
    def __init__(self, txt: str):
        self.s: A = None
        self.txt = txt

l = A("l")
e = B("e")
k = C("k")
g = D("g")
a = E("a")
n = F("n")
i = G("i")
j = H("j")
h = I("h")
f = J("f")

l.o = n
l.x = f
e.t = a
k.v = f
k.o = g
g.s = i
a.o = h
a.t = f
n.u = l
n.x = a
n.t = h
n.o = k
n.q = f
i.y = a
i.p = g
j.t = n
h.x = e
h.v = a
h.r = a
h.t = a
h.q = i
h.s = f
h.o = k
h.z = k
h.u = l
h.y = j
f.s = l
assert k.v.s.x.txt == "
class A:
    def __init__(self, txt: str):
        self.o: F = None
        self.x: J = None
        self.txt = txt

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

class C:
    def __init__(self, txt: str):
        self.v: J = None
        self.o: D = None
        self.txt = txt

class D:
    def __init__(self, txt: str):
        self.s: G = None
        self.txt = txt

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

class F:
    def __init__(self, txt: str):
        self.u: A = None
        self.x: E = None
        self.t: I = None
        self.o: C = None
        self.q: J = None
        self.txt = txt

class G:
    def __init__(self, txt: str):
        self.y: E = None
        self.p: D = None
        self.txt = txt

class H:
    def __init__(self, txt: str):
        self.t: F = None
        self.txt = txt

class I:
    def __init__(self, txt: str):
        self.x: B = None
        self.v: E = None
        self.q: G = None
        self.s: J = None
        self.o: C = None
        self.r: E = None
        self.u: A = None
        self.t: E = None
        self.z: C = None
        self.y: H = None
        self.txt = txt

class J:
    def __init__(self, txt: str):
        self.s: A = None
        self.txt = txt

l = A("l")
e = B("e")
k = C("k")
g = D("g")
a = E("a")
n = F("n")
i = G("i")
j = H("j")
h = I("h")
f = J("f")

l.o = n
l.x = f
e.t = a
k.v = f
k.o = g
g.s = i
a.o = h
a.t = f
n.u = l
n.x = a
n.t = h
n.o = k
n.q = f
i.y = a
i.p = g
j.t = n
h.x = e
h.v = a
h.r = a
h.t = a
h.q = i
h.s = f
h.o = k
h.z = k
h.u = l
h.y = j
f.s = l
assert k.v.s.x.txt == "f"