Buggy python submission (verdict: Runtime Error):
arr = []

for i in range(int(input())):
  command_line = input().split(" ")
  command = command_line[0]
  arg = ""
  if len(command_line) > 1: arg = command_line[1]

  if command == "insert":
    arr.insert(0, arg)
  if command == "delete":
    arr.remove(arg)
  if command == "deleteFirst":
    del arr[0]
  if command == "deleteLast":
    del arr[-1]

print(" ".join(arr))

Fixed submission:
from collections import deque

q = deque()

for i in range(int(input())):
  command_line = input().split(" ")
  command = command_line[0]
  arg = ""
  if len(command_line) > 1: arg = command_line[1]

  if command == "insert":
    q.appendleft(arg)
  elif command == "delete":
    try:
      q.remove(arg)
    except ValueError:
      pass
  elif command == "deleteFirst":
    q.popleft()
  else:
    q.pop()

print(" ".join(q))

Buggy python submission (verdict: Time Limit Exceeded):
arr = []

for i in range(int(input())):
  command_line = input().split(" ")
  command = command_line[0]
  arg = ""
  if len(command_line) > 1: arg = command_line[1]

  if command == "insert":
    arr.insert(0, arg)
  if command == "delete":
    if arg in arr: arr.remove(arg)
  if command == "deleteFirst":
    del arr[0]
  if command == "deleteLast":
    del arr[-1]

print(" ".join(arr))

Fixed submission:
from collections import deque

q = deque()

for i in range(int(input())):
  command_line = input().split(" ")
  command = command_line[0]
  arg = ""
  if len(command_line) > 1: arg = command_line[1]

  if command == "insert":
    q.appendleft(arg)
  elif command == "delete":
    try:
      q.remove(arg)
    except ValueError:
      pass
  elif command == "deleteFirst":
    q.popleft()
  else:
    q.pop()

print(" ".join(q))

Buggy python submission (verdict: Time Limit Exceeded):
from collections import deque

arr = []

for i in range(int(input())):
  command_line = input().split(" ")
  command = command_line[0]
  arg = ""
  if len(command_line) > 1: arg = command_line[1]

  if command == "insert":
    arr.insert(0, arg)
  if command == "delete":
    if arg in arr: arr.remove(arg)
  if command == "deleteFirst":
    arr.pop(0)
  if command == "deleteLast":
    arr.pop()

print(" ".join(arr))

Fixed submission:
from collections import deque

q = deque()

for i in range(int(input())):
  command_line = input().split(" ")
  command = command_line[0]
  arg = ""
  if len(command_line) > 1: arg = command_line[1]

  if command == "insert":
    q.appendleft(arg)
  elif command == "delete":
    try:
      q.remove(arg)
    except ValueError:
      pass
  elif command == "deleteFirst":
    q.popleft()
  else:
    q.pop()

print(" ".join(q))

Buggy python submission (verdict: Time Limit Exceeded):
from collections import deque

arr = []

for i in range(int(input())):
  command_line = input().split(" ")
  command = command_line[0]
  arg = ""
  if len(command_line) > 1: arg = command_line[1]

  if command == "insert":
    arr.insert(0, arg)
  if command == "delete":
    try:
      arr.remove(arg)
    except ValueError:
      pass
  if command == "deleteFirst":
    arr.pop(0)
  if command == "deleteLast":
    arr.pop()

print(" ".join(arr))

Fixed submission:
from collections import deque

q = deque()

for i in range(int(input())):
  command_line = input().split(" ")
  command = command_line[0]
  arg = ""
  if len(command_line) > 1: arg = command_line[1]

  if command == "insert":
    q.appendleft(arg)
  elif command == "delete":
    try:
      q.remove(arg)
    except ValueError:
      pass
  elif command == "deleteFirst":
    q.popleft()
  else:
    q.pop()

print(" ".join(q))