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

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

class C:
    def __init__(self, txt: str):
        self.p: A = None
        self.y: A = None
        self.x: G = None
        self.t: G = None
        self.txt = txt

class D:
    def __init__(self, txt: str):
        self.z: I = None
        self.r: H = None
        self.o: A = None
        self.s: A = None
        self.w: H = None
        self.q: H = None
        self.p: G = None
        self.v: E = None
        self.t: A = None
        self.txt = txt

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

class F:
    def __init__(self, txt: str):
        self.r: B = None
        self.w: I = None
        self.s: C = None
        self.o: A = None
        self.txt = txt

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

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

class I:
    def __init__(self, txt: str):
        self.v: C = None
        self.o: G = None
        self.s: G = None
        self.p: F = None
        self.z: G = None
        self.q: B = None
        self.x: G = None
        self.txt = txt

a = A("a")
j = B("j")
f = C("f")
i = D("i")
b = E("b")
m = F("m")
n = G("n")
l = H("l")
c = I("c")

a.u = b
j.p = b
f.p = a
f.y = a
f.x = n
f.t = n
i.z = c
i.r = l
i.w = l
i.q = l
i.o = a
i.s = a
i.t = a
i.p = n
i.v = b
b.p = c
b.q = n
m.r = j
m.w = c
m.s = f
m.o = a
n.u = i
l.u = j
c.v = f
c.o = n
c.s = n
c.z = n
c.x = n
c.p = m
c.q = j
assert b.q.u.p.u.t.u.txt == "
class A:
    def __init__(self, txt: str):
        self.u: E = None
        self.txt = txt

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

class C:
    def __init__(self, txt: str):
        self.p: A = None
        self.y: A = None
        self.x: G = None
        self.t: G = None
        self.txt = txt

class D:
    def __init__(self, txt: str):
        self.z: I = None
        self.r: H = None
        self.o: A = None
        self.s: A = None
        self.w: H = None
        self.q: H = None
        self.p: G = None
        self.v: E = None
        self.t: A = None
        self.txt = txt

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

class F:
    def __init__(self, txt: str):
        self.r: B = None
        self.w: I = None
        self.s: C = None
        self.o: A = None
        self.txt = txt

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

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

class I:
    def __init__(self, txt: str):
        self.v: C = None
        self.o: G = None
        self.s: G = None
        self.p: F = None
        self.z: G = None
        self.q: B = None
        self.x: G = None
        self.txt = txt

a = A("a")
j = B("j")
f = C("f")
i = D("i")
b = E("b")
m = F("m")
n = G("n")
l = H("l")
c = I("c")

a.u = b
j.p = b
f.p = a
f.y = a
f.x = n
f.t = n
i.z = c
i.r = l
i.w = l
i.q = l
i.o = a
i.s = a
i.t = a
i.p = n
i.v = b
b.p = c
b.q = n
m.r = j
m.w = c
m.s = f
m.o = a
n.u = i
l.u = j
c.v = f
c.o = n
c.s = n
c.z = n
c.x = n
c.p = m
c.q = j
assert b.q.u.p.u.t.u.txt == "b"