class Node:
    def __init__(self, data):
        self.data = data
        self.prev = None
        self.next = None


class IntList:
    def __init__(self, head):
        self.first = head
        self.last = head
        self.current = head
        while self.last and self.last.next:
            self.last = self.last.next

    def ToFirst(self):
        self.current = self.first

    def ToNext(self):
        if self.current and self.current.next:
            self.current = self.current.next

    def SetData(self, d):
        if self.current:
            self.current.data = d

    def IsLast(self):
        return self.current == self.last

    def process(self):
        self.ToFirst()
        index = 1
        count = 0
        while self.current:
            count += 1
            if index % 2 == 1:
                self.SetData(0)
            if self.IsLast():
                break
            self.ToNext()
            index += 1
        return count

    def print_list(self):
        cur = self.first
        res = []
        while cur:
            res.append(str(cur.data))
            cur = cur.next
        print("Список:", " ".join(res))


def create(arr):
    if not arr:
        return None
    head = Node(arr[0])
    cur = head
    for x in arr[1:]:
        n = Node(x)
        cur.next = n
        n.prev = cur
        cur = n
    return head


while True:
    try:
        print("\n1 - Ввести список\n0 - Выход")
        cmd = input("Выбор: ")
        if cmd == "0":
            break
        if cmd == "1":
            arr = list(map(int, input("Введите числа: ").split()))
            head = create(arr)
            lst = IntList(head)
            n = lst.process()
            print("Количество:", n)
            lst.print_list()
    except:
        print("Ошибка")