class A:
    def __init__(self, txt: str):
        self.o: I = None
        self.v: H = None
        self.r: B = None
        self.txt = txt

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

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

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

class E:
    def __init__(self, txt: str):
        self.x: C = None
        self.o: F = None
        self.r: F = None
        self.t: F = None
        self.p: G = None
        self.z: F = None
        self.txt = txt

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

class G:
    def __init__(self, txt: str):
        self.u: D = None
        self.x: I = None
        self.t: D = None
        self.v: A = None
        self.txt = txt

class H:
    def __init__(self, txt: str):
        self.v: B = None
        self.z: D = None
        self.u: A = None
        self.q: F = None
        self.p: C = None
        self.x: G = None
        self.txt = txt

class I:
    def __init__(self, txt: str):
        self.y: G = None
        self.p: F = None
        self.z: G = None
        self.txt = txt

d = A("d")
f = B("f")
i = C("i")
g = D("g")
h = E("h")
l = F("l")
e = G("e")
k = H("k")
b = I("b")

d.o = b
d.v = k
d.r = f
f.z = k
f.o = k
f.r = k
i.u = d
g.y = f
g.p = d
g.t = h
h.x = i
h.o = l
h.r = l
h.t = l
h.z = l
h.p = e
l.p = b
l.o = b
l.s = e
l.t = i
l.x = g
l.u = k
l.q = h
l.v = f
l.z = f
e.u = g
e.t = g
e.x = b
e.v = d
k.v = f
k.z = g
k.u = d
k.q = l
k.p = i
k.x = e
b.y = e
b.z = e
b.p = l
assert i.u.o.p.t.txt == "
class A:
    def __init__(self, txt: str):
        self.o: I = None
        self.v: H = None
        self.r: B = None
        self.txt = txt

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

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

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

class E:
    def __init__(self, txt: str):
        self.x: C = None
        self.o: F = None
        self.r: F = None
        self.t: F = None
        self.p: G = None
        self.z: F = None
        self.txt = txt

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

class G:
    def __init__(self, txt: str):
        self.u: D = None
        self.x: I = None
        self.t: D = None
        self.v: A = None
        self.txt = txt

class H:
    def __init__(self, txt: str):
        self.v: B = None
        self.z: D = None
        self.u: A = None
        self.q: F = None
        self.p: C = None
        self.x: G = None
        self.txt = txt

class I:
    def __init__(self, txt: str):
        self.y: G = None
        self.p: F = None
        self.z: G = None
        self.txt = txt

d = A("d")
f = B("f")
i = C("i")
g = D("g")
h = E("h")
l = F("l")
e = G("e")
k = H("k")
b = I("b")

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