class StackArray:
    def __init__(self):  # 建空棧
        self.array = []

    def is_empty(self):  # 棧的判空
        if len(self.array) == 0:  # 如果為零
            return 0
        else:
            return 1

    def push(self, value):  # 入棧
        i = len(self.array)
        if i == 0:  # 空棧
            print('空棧\n'
 
)
            return error
        else:
            self.array[i+1] = value
            return self.array

    def pop(self):  # 出棧
        i = len(self.array)
        if i == 0:
            print('空棧\n')
            return error
        else:
            value = self.array[i]
            self.array[i] = None
 

        return value

    def top(self):  # 檢視最後入棧的元素
        i = len(self.array)
        if i == 0:
            print('空棧\n')
            return error
        else:
            value = self.array[i]
        return value

    def show(self):  # 檢視棧的所有元素
        if len(self.array) == 0:
            print('空棧'
 
)
            return error
        else:
            i = 0
        while self.array[i] is not None:
            print(self.array[i],end='\n')
            i += 1
        return