.PHONY: clean test

all::
	make -C add $@
	make -C sub $@
	make -C mul $@
	make -C div $@
  
test::
	@make -C add $@
	@make -C sub $@
	@make -C mul $@
	@make -C div $@
 
clean::
	@make -C add clean
	@make -C sub clean
	@make -C mul clean
	@make -C div clean
