(VAR x1 )
(RULES 
        tower(0(x1)) -> s(0(p(s(p(s(x1))))))
        tower(s(x1)) -> p(s(p(s(twoto(p(s(p(s(tower(p(s(p(s(x1))))))))))))))
        twoto(0(x1)) -> s(0(x1))
        twoto(s(x1)) -> p(p(s(p(p(p(s(s(p(s(s(p(s(s(p(s(twice(p(s(p(s(p(p(p(s(s(s(twoto(p(s(p(s(x1))))))))))))))))))))))))))))))))
        twice(0(x1)) -> 0(x1)
        twice(s(x1)) -> p(p(p(s(s(s(s(s(twice(p(p(p(s(s(s(x1)))))))))))))))
        p(p(s(x1))) -> p(x1)
        p(s(x1)) -> x1
        p(0(x1)) -> 0(s(s(s(s(s(s(s(s(x1)))))))))
        
)