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

class B:
    def __init__(self, txt: str):
        self.t: F = None
        self.z: E = None
        self.q: F = None
        self.v: F = None
        self.txt = txt

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

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

class E:
    def __init__(self, txt: str):
        self.v: A = None
        self.s: A = None
        self.x: A = None
        self.txt = txt

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

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

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

class B:
    def __init__(self, txt: str):
        self.t: F = None
        self.z: E = None
        self.q: F = None
        self.v: F = None
        self.txt = txt

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

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

class E:
    def __init__(self, txt: str):
        self.v: A = None
        self.s: A = None
        self.x: A = None
        self.txt = txt

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

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

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