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

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

class C:
    def __init__(self, txt: str):
        self.z: D = None
        self.t: E = None
        self.s: F = None
        self.v: H = None
        self.w: E = None
        self.txt = txt

class D:
    def __init__(self, txt: str):
        self.u: I = None
        self.r: I = None
        self.q: E = None
        self.txt = txt

class E:
    def __init__(self, txt: str):
        self.s: F = None
        self.txt = txt

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

class G:
    def __init__(self, txt: str):
        self.q: I = None
        self.x: A = None
        self.o: J = None
        self.y: E = None
        self.u: D = None
        self.txt = txt

class H:
    def __init__(self, txt: str):
        self.q: F = None
        self.v: C = None
        self.txt = txt

class I:
    def __init__(self, txt: str):
        self.p: E = None
        self.t: B = None
        self.y: H = None
        self.w: D = None
        self.q: H = None
        self.o: G = None
        self.u: D = None
        self.x: A = None
        self.r: G = None
        self.txt = txt

class J:
    def __init__(self, txt: str):
        self.y: D = None
        self.u: I = None
        self.o: D = None
        self.txt = txt

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

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

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

class C:
    def __init__(self, txt: str):
        self.z: D = None
        self.t: E = None
        self.s: F = None
        self.v: H = None
        self.w: E = None
        self.txt = txt

class D:
    def __init__(self, txt: str):
        self.u: I = None
        self.r: I = None
        self.q: E = None
        self.txt = txt

class E:
    def __init__(self, txt: str):
        self.s: F = None
        self.txt = txt

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

class G:
    def __init__(self, txt: str):
        self.q: I = None
        self.x: A = None
        self.o: J = None
        self.y: E = None
        self.u: D = None
        self.txt = txt

class H:
    def __init__(self, txt: str):
        self.q: F = None
        self.v: C = None
        self.txt = txt

class I:
    def __init__(self, txt: str):
        self.p: E = None
        self.t: B = None
        self.y: H = None
        self.w: D = None
        self.q: H = None
        self.o: G = None
        self.u: D = None
        self.x: A = None
        self.r: G = None
        self.txt = txt

class J:
    def __init__(self, txt: str):
        self.y: D = None
        self.u: I = None
        self.o: D = None
        self.txt = txt

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

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