class A:
    def __init__(self, txt: str):
        self.o: C = None
        self.t: C = None
        self.p: I = None
        self.q: C = None
        self.y: F = None
        self.txt = txt

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

class C:
    def __init__(self, txt: str):
        self.u: A = None
        self.r: G = None
        self.o: H = None
        self.t: E = None
        self.txt = txt

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

class E:
    def __init__(self, txt: str):
        self.q: D = None
        self.r: H = None
        self.p: I = None
        self.v: C = None
        self.txt = txt

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

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

class H:
    def __init__(self, txt: str):
        self.v: I = None
        self.y: A = None
        self.q: G = None
        self.z: A = None
        self.txt = txt

class I:
    def __init__(self, txt: str):
        self.u: E = None
        self.v: H = None
        self.txt = txt

class J:
    def __init__(self, txt: str):
        self.z: C = None
        self.r: I = None
        self.y: I = None
        self.w: F = None
        self.q: F = None
        self.txt = txt

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

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

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

class C:
    def __init__(self, txt: str):
        self.u: A = None
        self.r: G = None
        self.o: H = None
        self.t: E = None
        self.txt = txt

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

class E:
    def __init__(self, txt: str):
        self.q: D = None
        self.r: H = None
        self.p: I = None
        self.v: C = None
        self.txt = txt

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

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

class H:
    def __init__(self, txt: str):
        self.v: I = None
        self.y: A = None
        self.q: G = None
        self.z: A = None
        self.txt = txt

class I:
    def __init__(self, txt: str):
        self.u: E = None
        self.v: H = None
        self.txt = txt

class J:
    def __init__(self, txt: str):
        self.z: C = None
        self.r: I = None
        self.y: I = None
        self.w: F = None
        self.q: F = None
        self.txt = txt

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

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