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

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

class C:
    def __init__(self, txt: str):
        self.z: D = None
        self.txt = txt

class D:
    def __init__(self, txt: str):
        self.r: G = None
        self.y: G = None
        self.x: B = None
        self.v: F = None
        self.q: F = None
        self.txt = txt

class E:
    def __init__(self, txt: str):
        self.p: A = None
        self.x: B = None
        self.w: E = None
        self.txt = txt

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

class G:
    def __init__(self, txt: str):
        self.v: C = None
        self.txt = txt

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

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

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

class C:
    def __init__(self, txt: str):
        self.z: D = None
        self.txt = txt

class D:
    def __init__(self, txt: str):
        self.r: G = None
        self.y: G = None
        self.x: B = None
        self.v: F = None
        self.q: F = None
        self.txt = txt

class E:
    def __init__(self, txt: str):
        self.p: A = None
        self.x: B = None
        self.w: E = None
        self.txt = txt

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

class G:
    def __init__(self, txt: str):
        self.v: C = None
        self.txt = txt

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

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