class A:
    def __init__(self, txt: str):
        self.v: B = None
        self.p: D = None
        self.y: A = None
        self.z: E = None
        self.w: F = None
        self.r: A = None
        self.txt = txt

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

class C:
    def __init__(self, txt: str):
        self.x: D = None
        self.u: E = None
        self.v: B = None
        self.txt = txt

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

class E:
    def __init__(self, txt: str):
        self.y: F = None
        self.u: F = None
        self.txt = txt

class F:
    def __init__(self, txt: str):
        self.p: A = None
        self.y: E = None
        self.t: E = None
        self.o: C = None
        self.txt = txt

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

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

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

class C:
    def __init__(self, txt: str):
        self.x: D = None
        self.u: E = None
        self.v: B = None
        self.txt = txt

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

class E:
    def __init__(self, txt: str):
        self.y: F = None
        self.u: F = None
        self.txt = txt

class F:
    def __init__(self, txt: str):
        self.p: A = None
        self.y: E = None
        self.t: E = None
        self.o: C = None
        self.txt = txt

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

b.v = g
b.p = j
b.y = l
b.r = l
b.z = n
b.w = i
g.o = n
g.p = e
g.x = e
g.u = i
e.x = j
e.u = n
e.v = g
f.y = j
n.y = i
n.u = i
i.p = b
i.y = n
i.t = c
i.o = e
j.y = f
l.v = g
l.p = f
l.y = b
l.r = b
l.z = n
l.w = i
c.y = i
c.u = i
assert b.p.y.y.txt == "j"