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

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

class C:
    def __init__(self, txt: str):
        self.u: A = None
        self.t: C = None
        self.o: D = None
        self.w: C = None
        self.s: C = None
        self.txt = txt

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

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

class F:
    def __init__(self, txt: str):
        self.s: A = None
        self.q: B = None
        self.y: B = None
        self.t: B = None
        self.o: E = None
        self.x: B = None
        self.txt = txt

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

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

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

class C:
    def __init__(self, txt: str):
        self.u: A = None
        self.t: C = None
        self.o: D = None
        self.w: C = None
        self.s: C = None
        self.txt = txt

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

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

class F:
    def __init__(self, txt: str):
        self.s: A = None
        self.q: B = None
        self.y: B = None
        self.t: B = None
        self.o: E = None
        self.x: B = None
        self.txt = txt

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

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