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

class B:
    def __init__(self, txt: str):
        self.q: D = None
        self.o: I = None
        self.z: C = None
        self.p: C = None
        self.u: I = None
        self.txt = txt

class C:
    def __init__(self, txt: str):
        self.v: E = None
        self.txt = txt

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

class E:
    def __init__(self, txt: str):
        self.y: C = None
        self.w: J = None
        self.txt = txt

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

class G:
    def __init__(self, txt: str):
        self.x: F = None
        self.u: J = None
        self.t: J = None
        self.txt = txt

class H:
    def __init__(self, txt: str):
        self.u: F = None
        self.w: A = None
        self.x: A = None
        self.z: J = None
        self.t: G = None
        self.txt = txt

class I:
    def __init__(self, txt: str):
        self.y: F = None
        self.r: E = None
        self.t: C = None
        self.u: E = None
        self.txt = txt

class J:
    def __init__(self, txt: str):
        self.v: B = None
        self.u: F = None
        self.y: D = None
        self.s: F = None
        self.x: A = None
        self.txt = txt

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

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

class B:
    def __init__(self, txt: str):
        self.q: D = None
        self.o: I = None
        self.z: C = None
        self.p: C = None
        self.u: I = None
        self.txt = txt

class C:
    def __init__(self, txt: str):
        self.v: E = None
        self.txt = txt

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

class E:
    def __init__(self, txt: str):
        self.y: C = None
        self.w: J = None
        self.txt = txt

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

class G:
    def __init__(self, txt: str):
        self.x: F = None
        self.u: J = None
        self.t: J = None
        self.txt = txt

class H:
    def __init__(self, txt: str):
        self.u: F = None
        self.w: A = None
        self.x: A = None
        self.z: J = None
        self.t: G = None
        self.txt = txt

class I:
    def __init__(self, txt: str):
        self.y: F = None
        self.r: E = None
        self.t: C = None
        self.u: E = None
        self.txt = txt

class J:
    def __init__(self, txt: str):
        self.v: B = None
        self.u: F = None
        self.y: D = None
        self.s: F = None
        self.x: A = None
        self.txt = txt

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

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