class A:
    def __init__(self, txt: str):
        self.v: B = None
        self.y: I = None
        self.u: B = None
        self.txt = txt

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

class C:
    def __init__(self, txt: str):
        self.y: G = None
        self.x: B = None
        self.o: G = None
        self.r: H = None
        self.s: D = None
        self.v: E = None
        self.txt = txt

class D:
    def __init__(self, txt: str):
        self.x: F = None
        self.p: C = None
        self.w: E = None
        self.s: B = None
        self.y: F = None
        self.o: B = None
        self.z: C = None
        self.t: E = None
        self.r: H = None
        self.txt = txt

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

class F:
    def __init__(self, txt: str):
        self.w: D = None
        self.v: G = None
        self.s: A = None
        self.o: C = None
        self.txt = txt

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

class H:
    def __init__(self, txt: str):
        self.q: F = None
        self.p: E = None
        self.z: C = None
        self.x: B = None
        self.r: E = None
        self.w: D = None
        self.txt = txt

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

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

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

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

class C:
    def __init__(self, txt: str):
        self.y: G = None
        self.x: B = None
        self.o: G = None
        self.r: H = None
        self.s: D = None
        self.v: E = None
        self.txt = txt

class D:
    def __init__(self, txt: str):
        self.x: F = None
        self.p: C = None
        self.w: E = None
        self.s: B = None
        self.y: F = None
        self.o: B = None
        self.z: C = None
        self.t: E = None
        self.r: H = None
        self.txt = txt

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

class F:
    def __init__(self, txt: str):
        self.w: D = None
        self.v: G = None
        self.s: A = None
        self.o: C = None
        self.txt = txt

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

class H:
    def __init__(self, txt: str):
        self.q: F = None
        self.p: E = None
        self.z: C = None
        self.x: B = None
        self.r: E = None
        self.w: D = None
        self.txt = txt

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

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

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