(VAR x)
(RULES
 T(t(x)) -> x
 t(T(x)) -> x
 S(s(x)) -> x
 s(S(x)) -> x
 R(r(x)) -> x
 r(R(x)) -> x
 t(t(S(T(s(T(r(t(R(R(S(t(s(T(T(r(r(T(R(t(r(r(T(R(t(x))))))))))))))))))))))))) -> x
 r(r(T(R(t(R(s(r(S(S(T(r(t(R(R(s(s(R(S(r(s(s(R(S(r(x))))))))))))))))))))))))) -> x
 s(s(R(S(r(S(t(s(T(T(R(s(r(S(S(t(t(S(T(s(t(t(S(T(s(x))))))))))))))))))))))))) -> x
)