이 코드보고 객체지향 뭔지 암 ㅇㅅㅇ
덱을 구현하는 간단나노한 코드데스

import sys

class deque:
        def __init__(self):
                self.li = list()
                self.cnt = 0

        def push_front(self,x):
                self.cnt = self.cnt + 1
                self.li = [x]+self.li
                return

        def push_back(self,x):
                self.cnt = self.cnt + 1
                self.li.append(x)
                return

        def pop_front(self):
                if self.cnt == 0:
                        print(-1)
                        return -1

                print(self.li[0])
                self.cnt = self.cnt-1
                return self.li.pop(0)

        def pop_back(self):
                if self.cnt == 0:
                        print(-1)
                        return -1

                print(self.li[self.cnt-1])
                self.cnt = self.cnt-1
                self.li.pop()
                return self.li

        def front(self):
                if self.cnt == 0:
                        print(-1)
                        return -1
                else:
                        print(self.li[0])
                        return self.li[0]

        def back(self):
                if self.cnt == 0:
                        print(-1)
                        return -1
                else:
                        print(self.li[self.cnt-1])
                        return self.li[self.cnt-1]

        def empty(self):
                if self.cnt == 0:
                        print(1)
                        return 1
                else:
                        print(0)
                        return 0

        def size(self):
                print(self.cnt)
                return self.cnt