20240623

# a = list(input())
# stack1 = []
# result = 0
# running = True

# for i in a:
#     stack1_index = len(stack1) - 1
#     if running == False:
#         break
    
#     if len(stack1) == 0 or i == "(" or i == "[" :
#         stack1.append(i)
#         stack1_index += 1
#         continue
    
#     while True:  
#         if i == ")" or i == "]":
#             stack1_pop = stack1.pop()
#             stack1_index -= 1
            
#             if stack1_pop == "(" and result == 0 and i != "]":
#                 stack1.append(2)
#                 break
            
#             elif stack1_pop == "(" and result != 0 and i != "]":
#                 result *= 2
#                 stack1.append(result)
#                 result = 0
#                 break
    
#             elif stack1_pop == "[" and result == 0 and i != ")":
#                 stack1.append(3)
#                 break
            
#             elif  stack1_pop == "[" and result != 0 and i != ")":
#                 result *= 3
#                 stack1.append(result)
#                 result = 0
#                 break
            
#             elif isinstance(stack1_pop, int):
#                 result += stack1_pop
#                 continue
            
#         print(0)
#         running = False
#         break
            
# if  running:
#     for j in stack1 :
#         if isinstance(j, str):
#             print(0)
#             running = False
#             break
    
# if running:
#     print(sum(stack1))

# list = [5,4,3,3,2,3,1]

# # 리스트의 마지막 원소 제거 
# list.pop()
# print(list)

# #리스트의 첫번째 원소 제거
# del list[0]
# print(list)

# #리스트에서 3 값을 찾아서 제거 (최초로 만난 거만)
# list.remove(3)
# print(list)

# n = int(input())
# queue = []

# for count in range(n):
#     command = input()
    
#     if command[:4] == "push":
#         queue.append(command.split()[1])
    
#     elif command == "front()":
#         if len(queue) == 0:
#             print(-1)
#         else:
#             print(queue[0])
    
#     elif command =="back()":
#         if len(queue) == 0:
#             print(-1)
#         else:
#             print(queue[-1])
    
#     elif command == "pop()":
#         if len(queue) == 0:
#             continue
#         else:
#             del queue[0]
    
#     elif command == "size()":
#         print(len(queue))
    
#     elif command == "empty()":
#         if queue:
#             print("false")
#         else:
#             print("true")