class A:
    def __init__(self, txt: str):
        self.v: A = None
        self.z: C = None
        self.t: A = None
        self.p: A = None
        self.y: E = None
        self.txt = txt

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

class C:
    def __init__(self, txt: str):
        self.r: C = None
        self.y: C = None
        self.p: D = None
        self.o: E = None
        self.u: A = None
        self.w: C = None
        self.txt = txt

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

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

class F:
    def __init__(self, txt: str):
        self.v: B = None
        self.p: B = None
        self.t: E = None
        self.z: C = None
        self.o: B = None
        self.txt = txt

d = A("d")
e = B("e")
c = C("c")
k = D("k")
b = E("b")
i = F("i")
f = E("f")
n = C("n")
a = A("a")

d.v = a
d.t = a
d.p = a
d.z = n
d.y = f
e.o = i
e.r = k
c.r = n
c.y = n
c.w = n
c.p = k
c.o = b
c.u = a
k.o = b
k.r = e
b.o = i
b.s = e
i.v = e
i.p = e
i.o = e
i.t = b
i.z = c
f.o = i
f.s = e
n.r = c
n.y = c
n.w = c
n.p = k
n.o = b
n.u = d
a.v = d
a.t = d
a.p = d
a.z = n
a.y = f
assert e.o.p.r.o.o.z.u.p.txt == "
class A:
    def __init__(self, txt: str):
        self.v: A = None
        self.z: C = None
        self.t: A = None
        self.p: A = None
        self.y: E = None
        self.txt = txt

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

class C:
    def __init__(self, txt: str):
        self.r: C = None
        self.y: C = None
        self.p: D = None
        self.o: E = None
        self.u: A = None
        self.w: C = None
        self.txt = txt

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

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

class F:
    def __init__(self, txt: str):
        self.v: B = None
        self.p: B = None
        self.t: E = None
        self.z: C = None
        self.o: B = None
        self.txt = txt

d = A("d")
e = B("e")
c = C("c")
k = D("k")
b = E("b")
i = F("i")
f = E("f")
n = C("n")
a = A("a")

d.v = a
d.t = a
d.p = a
d.z = n
d.y = f
e.o = i
e.r = k
c.r = n
c.y = n
c.w = n
c.p = k
c.o = b
c.u = a
k.o = b
k.r = e
b.o = i
b.s = e
i.v = e
i.p = e
i.o = e
i.t = b
i.z = c
f.o = i
f.s = e
n.r = c
n.y = c
n.w = c
n.p = k
n.o = b
n.u = d
a.v = d
a.t = d
a.p = d
a.z = n
a.y = f
assert e.o.p.r.o.o.z.u.p.txt == "d"