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

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

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

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

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

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

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

i.z = n
i.s = n
i.y = e
n.u = i
n.s = k
n.t = k
n.y = e
n.o = c
n.q = b
g.r = d
g.v = b
g.p = l
g.x = i
b.o = n
b.v = d
b.t = d
b.r = g
d.s = c
d.r = l
c.p = i
c.y = g
c.r = n
e.o = n
e.v = d
e.t = l
e.r = k
l.s = c
l.r = d
k.r = l
k.v = b
k.p = d
k.x = i
assert n.o.r.y.txt == "
class A:
    def __init__(self, txt: str):
        self.z: B = None
        self.y: D = None
        self.s: B = None
        self.txt = txt

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

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

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

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

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

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

i.z = n
i.s = n
i.y = e
n.u = i
n.s = k
n.t = k
n.y = e
n.o = c
n.q = b
g.r = d
g.v = b
g.p = l
g.x = i
b.o = n
b.v = d
b.t = d
b.r = g
d.s = c
d.r = l
c.p = i
c.y = g
c.r = n
e.o = n
e.v = d
e.t = l
e.r = k
l.s = c
l.r = d
k.r = l
k.v = b
k.p = d
k.x = i
assert n.o.r.y.txt == "e"