DIRS = problem1 problem2 problem3 problem4 problem5

top:
	@my_status=0
	@for dir in $(DIRS) ; \
	do \
	(cd $$dir ; $(MAKE)) ; \
	my_status=$$? ; \
	if [ $$my_status -ne 0 ] ; then exit 1 ; fi ; \
	done
	@exit $$my_status

clean:
	@for dir in $(DIRS) ; \
	do \
	(cd $$dir ; \
	$(MAKE) clean ; \
	cd ..) ; \
	done
