class A:
    def __init__(self, txt: str):
        self.x: E = None
        self.txt = txt

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

class C:
    def __init__(self, txt: str):
        self.r: H = None
        self.txt = txt

class D:
    def __init__(self, txt: str):
        self.o: A = None
        self.txt = txt

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

class F:
    def __init__(self, txt: str):
        self.p: G = None
        self.u: I = None
        self.s: E = None
        self.z: E = None
        self.y: D = None
        self.o: E = None
        self.r: G = None
        self.txt = txt

class G:
    def __init__(self, txt: str):
        self.s: A = None
        self.z: A = None
        self.p: H = None
        self.v: D = None
        self.txt = txt

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

class I:
    def __init__(self, txt: str):
        self.s: F = None
        self.q: F = None
        self.w: F = None
        self.u: G = None
        self.t: D = None
        self.v: C = None
        self.txt = txt

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

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

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

class C:
    def __init__(self, txt: str):
        self.r: H = None
        self.txt = txt

class D:
    def __init__(self, txt: str):
        self.o: A = None
        self.txt = txt

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

class F:
    def __init__(self, txt: str):
        self.p: G = None
        self.u: I = None
        self.s: E = None
        self.z: E = None
        self.y: D = None
        self.o: E = None
        self.r: G = None
        self.txt = txt

class G:
    def __init__(self, txt: str):
        self.s: A = None
        self.z: A = None
        self.p: H = None
        self.v: D = None
        self.txt = txt

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

class I:
    def __init__(self, txt: str):
        self.s: F = None
        self.q: F = None
        self.w: F = None
        self.u: G = None
        self.t: D = None
        self.v: C = None
        self.txt = txt

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

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