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

class B:
    def __init__(self, txt: str):
        self.s: F = None
        self.t: G = None
        self.u: A = None
        self.z: G = None
        self.txt = txt

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

class D:
    def __init__(self, txt: str):
        self.t: A = None
        self.y: B = None
        self.v: F = None
        self.q: A = None
        self.s: E = None
        self.txt = txt

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

class F:
    def __init__(self, txt: str):
        self.w: F = None
        self.o: D = None
        self.z: G = None
        self.s: D = None
        self.x: D = None
        self.txt = txt

class G:
    def __init__(self, txt: str):
        self.t: G = None
        self.x: D = None
        self.txt = txt

f = A("f")
j = B("j")
i = C("i")
b = D("b")
c = E("c")
k = F("k")
m = G("m")
g = F("g")
l = G("l")

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

class B:
    def __init__(self, txt: str):
        self.s: F = None
        self.t: G = None
        self.u: A = None
        self.z: G = None
        self.txt = txt

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

class D:
    def __init__(self, txt: str):
        self.t: A = None
        self.y: B = None
        self.v: F = None
        self.q: A = None
        self.s: E = None
        self.txt = txt

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

class F:
    def __init__(self, txt: str):
        self.w: F = None
        self.o: D = None
        self.z: G = None
        self.s: D = None
        self.x: D = None
        self.txt = txt

class G:
    def __init__(self, txt: str):
        self.t: G = None
        self.x: D = None
        self.txt = txt

f = A("f")
j = B("j")
i = C("i")
b = D("b")
c = E("c")
k = F("k")
m = G("m")
g = F("g")
l = G("l")

f.x = c
f.v = c
f.y = b
j.s = g
j.t = m
j.u = f
j.z = l
i.o = j
b.t = f
b.q = f
b.y = j
b.v = k
b.s = c
c.t = k
c.q = i
c.u = b
k.w = g
k.o = b
k.s = b
k.x = b
k.z = l
m.t = l
m.x = b
g.w = k
g.o = b
g.s = b
g.x = b
g.z = m
l.t = m
l.x = b
assert f.x.u.y.z.txt == "l"