while 1:
 s=[];p=e=0;i=raw_input()
 for c in i:
	b=")]}>([{".find(c)
	if b/4:s+=[b%4]
	elif b%4-s.pop():e=i[p:];break
	p+=1
 print(s or e)and"failed at: "+(e or"EOL")or"yes"