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

class B:
    def __init__(self, txt: str):
        self.y: E = None
        self.z: F = None
        self.w: C = None
        self.v: C = None
        self.r: F = None
        self.s: C = None
        self.p: G = None
        self.txt = txt

class C:
    def __init__(self, txt: str):
        self.r: C = None
        self.s: C = None
        self.q: F = None
        self.u: C = None
        self.z: C = None
        self.v: A = None
        self.txt = txt

class D:
    def __init__(self, txt: str):
        self.p: A = None
        self.txt = txt

class E:
    def __init__(self, txt: str):
        self.s: B = None
        self.r: A = None
        self.z: F = None
        self.o: B = None
        self.txt = txt

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

class G:
    def __init__(self, txt: str):
        self.r: D = None
        self.w: F = None
        self.z: E = None
        self.o: A = None
        self.y: D = None
        self.t: G = None
        self.txt = txt

k = A("k")
j = B("j")
f = C("f")
d = D("d")
n = E("n")
e = F("e")
l = G("l")
m = G("m")
i = C("i")

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

class B:
    def __init__(self, txt: str):
        self.y: E = None
        self.z: F = None
        self.w: C = None
        self.v: C = None
        self.r: F = None
        self.s: C = None
        self.p: G = None
        self.txt = txt

class C:
    def __init__(self, txt: str):
        self.r: C = None
        self.s: C = None
        self.q: F = None
        self.u: C = None
        self.z: C = None
        self.v: A = None
        self.txt = txt

class D:
    def __init__(self, txt: str):
        self.p: A = None
        self.txt = txt

class E:
    def __init__(self, txt: str):
        self.s: B = None
        self.r: A = None
        self.z: F = None
        self.o: B = None
        self.txt = txt

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

class G:
    def __init__(self, txt: str):
        self.r: D = None
        self.w: F = None
        self.z: E = None
        self.o: A = None
        self.y: D = None
        self.t: G = None
        self.txt = txt

k = A("k")
j = B("j")
f = C("f")
d = D("d")
n = E("n")
e = F("e")
l = G("l")
m = G("m")
i = C("i")

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