class A:
    def __init__(self, txt: str):
        self.o: C = None
        self.z: A = None
        self.r: C = None
        self.txt = txt

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

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

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

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

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

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

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

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

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

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

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

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

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

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