class A:
    def __init__(self, txt: str):
        self.s: D = None
        self.w: A = None
        self.x: D = None
        self.v: B = None
        self.txt = txt

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

class C:
    def __init__(self, txt: str):
        self.u: F = None
        self.o: B = None
        self.r: C = None
        self.txt = txt

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

class E:
    def __init__(self, txt: str):
        self.z: E = None
        self.p: E = None
        self.o: E = None
        self.t: E = None
        self.s: E = None
        self.r: E = None
        self.txt = txt

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

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

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

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

class C:
    def __init__(self, txt: str):
        self.u: F = None
        self.o: B = None
        self.r: C = None
        self.txt = txt

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

class E:
    def __init__(self, txt: str):
        self.z: E = None
        self.p: E = None
        self.o: E = None
        self.t: E = None
        self.s: E = None
        self.r: E = None
        self.txt = txt

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

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

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