class A:
    def __init__(self, txt: str):
        self.z: D = None
        self.y: C = None
        self.s: C = None
        self.r: F = None
        self.t: F = None
        self.txt = txt

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

class C:
    def __init__(self, txt: str):
        self.u: G = None
        self.t: F = None
        self.o: F = None
        self.w: F = None
        self.p: F = None
        self.y: G = None
        self.z: E = None
        self.txt = txt

class D:
    def __init__(self, txt: str):
        self.p: E = None
        self.y: F = None
        self.o: G = None
        self.s: F = None
        self.u: F = None
        self.txt = txt

class E:
    def __init__(self, txt: str):
        self.w: C = None
        self.o: G = None
        self.u: C = None
        self.s: F = None
        self.txt = txt

class F:
    def __init__(self, txt: str):
        self.y: C = None
        self.txt = txt

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

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

i.z = a
i.y = b
i.s = b
i.r = c
i.t = c
n.w = l
n.s = a
b.u = l
b.y = l
b.t = c
b.o = c
b.w = c
b.p = c
b.z = d
a.p = d
a.y = c
a.s = c
a.u = c
a.o = l
d.w = b
d.u = b
d.o = l
d.s = c
c.y = b
l.r = c
l.u = n
j.w = b
j.u = b
j.o = l
j.s = c
assert b.u.r.y.txt == "
class A:
    def __init__(self, txt: str):
        self.z: D = None
        self.y: C = None
        self.s: C = None
        self.r: F = None
        self.t: F = None
        self.txt = txt

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

class C:
    def __init__(self, txt: str):
        self.u: G = None
        self.t: F = None
        self.o: F = None
        self.w: F = None
        self.p: F = None
        self.y: G = None
        self.z: E = None
        self.txt = txt

class D:
    def __init__(self, txt: str):
        self.p: E = None
        self.y: F = None
        self.o: G = None
        self.s: F = None
        self.u: F = None
        self.txt = txt

class E:
    def __init__(self, txt: str):
        self.w: C = None
        self.o: G = None
        self.u: C = None
        self.s: F = None
        self.txt = txt

class F:
    def __init__(self, txt: str):
        self.y: C = None
        self.txt = txt

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

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

i.z = a
i.y = b
i.s = b
i.r = c
i.t = c
n.w = l
n.s = a
b.u = l
b.y = l
b.t = c
b.o = c
b.w = c
b.p = c
b.z = d
a.p = d
a.y = c
a.s = c
a.u = c
a.o = l
d.w = b
d.u = b
d.o = l
d.s = c
c.y = b
l.r = c
l.u = n
j.w = b
j.u = b
j.o = l
j.s = c
assert b.u.r.y.txt == "b"