frontier=util.Stack()
    frontier.push(problem.getStartState())
    mylist=[]
    while True:
        if frontier.isEmpty():
            return []
        current=frontier.pop()
        print 'current'
        print current
        if problem.isGoalState(current)==True:
        	return mylist
        mylist.append(current)
        info=problem.getSuccessors(current)
        info.sort()
       	for i in info:
        	st=i[0]
        	moment_list=[]
        	while True:
        		if frontier.isEmpty()==True:
        			break
        		re=frontier.pop()
        		moment_list.append(re)
        	for k in range(len(moment_list),0):
        		frontier.push(moment_list[k])
        	print 'moment_list'
        	print moment_list
        	print 'st'
        	print st
        	if st in mylist:
        		if st in moment_list:
        			continue
        		else:
        			frontier.push(st)
        	else:
        		frontier.push(st)