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

    def length(self):
        # Rekursive Methode zur Berechnung der Länge
        if self.next is None:
            return 1
        else:
            return 1 + self.next.length()


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

    def insert(self, value):
        new_element = Element(value)
        new_element.next = self.head
        self.head = new_element

    def remove_first(self):
        if self.head is not None:
            self.head = self.head.next

    def length(self):
        if self.head is None:
            return 0
        else:
            return self.head.length()

    def show_list(self):
        current = self.head
        while current is not None:
            print(current.data)
            current = current.next

    def search(self, value):
        current = self.head
        while current is not None:
            if current.data == value:
                return current
            current = current.next
        return None

    def insert_before(self, value, comp_value):
        new_element = Element(value)
        if self.head is None:
            return

        if self.head.data == comp_value:
            new_element.next = self.head
            self.head = new_element
            return

        current = self.head
        while current.next is not None and current.next.data != comp_value:
            current = current.next

        if current.next is not None:
            new_element.next = current.next
            current.next = new_element