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

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

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

class D:
    def __init__(self, txt: str):
        self.z: G = None
        self.r: C = None
        self.w: C = None
        self.u: A = None
        self.v: B = None
        self.txt = txt

class E:
    def __init__(self, txt: str):
        self.o: D = None
        self.r: C = None
        self.s: G = None
        self.x: A = None
        self.y: B = None
        self.q: C = None
        self.z: C = None
        self.w: C = None
        self.txt = txt

class F:
    def __init__(self, txt: str):
        self.r: D = None
        self.x: A = None
        self.txt = txt

class G:
    def __init__(self, txt: str):
        self.x: C = None
        self.y: H = None
        self.t: A = None
        self.r: H = None
        self.v: B = None
        self.txt = txt

class H:
    def __init__(self, txt: str):
        self.r: G = None
        self.u: E = None
        self.v: I = None
        self.y: G = None
        self.s: C = None
        self.z: I = None
        self.t: E = None
        self.txt = txt

class I:
    def __init__(self, txt: str):
        self.s: G = None
        self.z: D = None
        self.y: D = None
        self.p: A = None
        self.x: B = None
        self.v: H = None
        self.o: B = None
        self.w: H = None
        self.txt = txt

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

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

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

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

class D:
    def __init__(self, txt: str):
        self.z: G = None
        self.r: C = None
        self.w: C = None
        self.u: A = None
        self.v: B = None
        self.txt = txt

class E:
    def __init__(self, txt: str):
        self.o: D = None
        self.r: C = None
        self.s: G = None
        self.x: A = None
        self.y: B = None
        self.q: C = None
        self.z: C = None
        self.w: C = None
        self.txt = txt

class F:
    def __init__(self, txt: str):
        self.r: D = None
        self.x: A = None
        self.txt = txt

class G:
    def __init__(self, txt: str):
        self.x: C = None
        self.y: H = None
        self.t: A = None
        self.r: H = None
        self.v: B = None
        self.txt = txt

class H:
    def __init__(self, txt: str):
        self.r: G = None
        self.u: E = None
        self.v: I = None
        self.y: G = None
        self.s: C = None
        self.z: I = None
        self.t: E = None
        self.txt = txt

class I:
    def __init__(self, txt: str):
        self.s: G = None
        self.z: D = None
        self.y: D = None
        self.p: A = None
        self.x: B = None
        self.v: H = None
        self.o: B = None
        self.w: H = None
        self.txt = txt

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

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