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

class B:
    def __init__(self, txt: str):
        self.z: E = None
        self.x: E = None
        self.s: B = None
        self.w: F = None
        self.p: C = None
        self.t: B = None
        self.txt = txt

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

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

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

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

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

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

class B:
    def __init__(self, txt: str):
        self.z: E = None
        self.x: E = None
        self.s: B = None
        self.w: F = None
        self.p: C = None
        self.t: B = None
        self.txt = txt

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

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

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

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

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

j.s = l
j.u = l
j.v = c
j.y = b
k.z = l
k.x = l
k.s = i
k.t = i
k.w = e
k.p = f
f.r = c
f.x = b
f.w = l
a.u = l
a.q = b
a.z = b
a.v = i
a.w = e
a.t = e
l.r = k
e.s = i
e.z = k
b.s = i
b.z = i
m.r = j
m.x = e
m.w = l
i.z = l
i.x = l
i.s = k
i.t = k
i.w = b
i.p = m
c.s = l
c.u = l
c.v = j
c.y = b
assert j.v.v.v.u.r.s.w.s.t.txt == "k"