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

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

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

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

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

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

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

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

j.y = m
j.x = a
j.q = k
j.s = f
j.p = i
j.u = c
b.o = g
b.s = d
b.v = d
b.x = m
f.s = c
f.r = m
f.z = m
i.z = g
i.t = g
i.x = m
i.v = d
g.t = k
g.q = a
g.x = d
g.y = f
g.v = b
g.s = c
a.q = b
a.x = g
a.u = d
k.r = b
m.o = d
m.s = d
m.v = g
m.x = b
d.t = k
d.q = a
d.x = g
d.y = f
d.v = m
d.s = j
c.y = m
c.x = a
c.q = k
c.s = f
c.p = i
c.u = j
assert i.t.t.r.s.y.r.o.q.q.txt == "
class A:
    def __init__(self, txt: str):
        self.y: B = None
        self.x: F = None
        self.q: G = None
        self.s: C = None
        self.p: D = None
        self.u: A = None
        self.txt = txt

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

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

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

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

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

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

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

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