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

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

class C:
    def __init__(self, txt: str):
        self.o: E = None
        self.r: F = None
        self.q: D = None
        self.w: A = None
        self.x: E = None
        self.z: B = None
        self.txt = txt

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

class E:
    def __init__(self, txt: str):
        self.q: D = None
        self.r: A = None
        self.u: D = None
        self.t: D = None
        self.x: D = None
        self.o: B = None
        self.txt = txt

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

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

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

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

class C:
    def __init__(self, txt: str):
        self.o: E = None
        self.r: F = None
        self.q: D = None
        self.w: A = None
        self.x: E = None
        self.z: B = None
        self.txt = txt

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

class E:
    def __init__(self, txt: str):
        self.q: D = None
        self.r: A = None
        self.u: D = None
        self.t: D = None
        self.x: D = None
        self.o: B = None
        self.txt = txt

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

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

c.z = e
c.s = e
c.x = k
e.o = f
k.o = d
k.x = d
k.r = i
k.q = n
k.w = c
k.z = e
f.y = c
f.t = c
f.r = c
f.q = c
f.o = n
f.z = d
d.q = n
d.r = c
d.u = f
d.t = f
d.x = f
d.o = e
i.r = c
n.y = c
n.t = c
n.r = c
n.q = c
n.o = f
n.z = d
l.o = f
assert c.z.o.y.s.o.t.s.o.txt == "f"