sequence = input() stack = [] flag = True for ch in sequence: if ch in "({[": stack.append(ch) else: if len(stack) == 0: flag = False break last_opening_bracket = stack.pop() pair = f"{last_opening_bracket}{ch}" if pair not in "(){}[]": flag = False break if flag and len(stack) == 0: print("YES") else: print("NO")