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

class B:
    def __init__(self, txt: str):
        self.s: C = None
        self.txt = txt

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

class D:
    def __init__(self, txt: str):
        self.r: E = None
        self.x: F = None
        self.w: F = None
        self.y: F = None
        self.txt = txt

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

class F:
    def __init__(self, txt: str):
        self.u: C = None
        self.p: D = None
        self.z: A = None
        self.t: D = None
        self.txt = txt

l = A("l")
c = B("c")
n = C("n")
a = D("a")
e = E("e")
m = F("m")
g = A("g")
k = A("k")
i = F("i")
f = B("f")

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

class B:
    def __init__(self, txt: str):
        self.s: C = None
        self.txt = txt

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

class D:
    def __init__(self, txt: str):
        self.r: E = None
        self.x: F = None
        self.w: F = None
        self.y: F = None
        self.txt = txt

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

class F:
    def __init__(self, txt: str):
        self.u: C = None
        self.p: D = None
        self.z: A = None
        self.t: D = None
        self.txt = txt

l = A("l")
c = B("c")
n = C("n")
a = D("a")
e = E("e")
m = F("m")
g = A("g")
k = A("k")
i = F("i")
f = B("f")

l.o = a
l.z = a
l.y = a
l.t = e
l.v = e
c.s = n
n.r = a
n.t = c
n.u = i
a.r = e
a.x = m
a.w = m
a.y = i
e.t = a
e.x = m
e.r = f
m.u = n
m.p = a
m.t = a
m.z = l
g.o = a
g.z = a
g.y = a
g.t = e
g.v = e
k.o = a
k.z = a
k.y = a
k.t = e
k.v = e
i.u = n
i.p = a
i.t = a
i.z = g
f.s = n
assert e.x.u.t.s.t.s.u.txt == "i"