class Node:
    def __init__(self, data: int | float | list | dict | tuple | set):
        self.data = data
        self.next = None
        self.prev = None

class DoublyLinkedList:
    def __init__(self):
        self.head = None

    def append(self, data):
        """Add a node with the given data to the end of the list."""
        new_node = Node(data)
        if not self.head:
            self.head = new_node
            return
        curr = self.head
        while curr.next:
            curr = curr.next
        curr.next = new_node
        new_node.prev = curr

    def prepend(self, data):
        """Add a node with the given data to the beginning of the list."""
        new_node = Node(data)
        if self.head:
            self.head.prev = new_node
        new_node.next = self.head
        self.head = new_node

    def insert_at_position(self, position, data):
        """Insert a node with the given data at the specified position (0-based)."""
        if position <= 0 or not self.head:
            self.prepend(data)
            return
        new_node = Node(data)
        curr = self.head
        index = 0
        while curr.next and index < position - 1:
            curr = curr.next
            index += 1
        new_node.next = curr.next
        new_node.prev = curr
        if curr.next:
            curr.next.prev = new_node
        curr.next = new_node

    def delete_value(self, value):
        """Remove the first node that contains the specified value."""
        curr = self.head
        while curr:
            if curr.data == value:
                if curr.prev:
                    curr.prev.next = curr.next
                else:
                    self.head = curr.next
                if curr.next:
                    curr.next.prev = curr.prev
                return True
            curr = curr.next
        return False

    def search(self, value):
        """Return True if a node with the specified value exists, otherwise False."""
        curr = self.head
        while curr:
            if curr.data == value:
                return True
            curr = curr.next
        return False

    def print_list(self):
        """Print all elements in the list in order."""
        elems = []
        curr = self.head
        while curr:
            elems.append(str(curr.data))
            curr = curr.next
        print(" <-> ".join(elems))