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

class B:
    def __init__(self, txt: str):
        self.x: B = None
        self.q: C = None
        self.p: F = None
        self.w: E = None
        self.o: F = None
        self.v: D = None
        self.s: C = None
        self.txt = txt

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

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

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

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

class G:
    def __init__(self, txt: str):
        self.w: A = None
        self.u: E = None
        self.r: B = None
        self.v: B = None
        self.t: F = None
        self.txt = txt

c = A("c")
a = B("a")
h = C("h")
e = D("e")
i = E("i")
l = F("l")
b = G("b")
j = B("j")

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

class B:
    def __init__(self, txt: str):
        self.x: B = None
        self.q: C = None
        self.p: F = None
        self.w: E = None
        self.o: F = None
        self.v: D = None
        self.s: C = None
        self.txt = txt

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

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

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

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

class G:
    def __init__(self, txt: str):
        self.w: A = None
        self.u: E = None
        self.r: B = None
        self.v: B = None
        self.t: F = None
        self.txt = txt

c = A("c")
a = B("a")
h = C("h")
e = D("e")
i = E("i")
l = F("l")
b = G("b")
j = B("j")

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