from typing import Self


class Node:
    def __init__(self, data: int):
        self.data: int = data
        self.next: Self | None = None


class LinkedList:
    def __init__(self):
        self.head: Node | None = None

    # Definition der "append" Methode ich mag push und pop lieber >:)
    def push(self, data: int):
        if self.head is None:
            self.head = Node(data)
            return

        node = self.head
        assert node is not None

        while True:
            if node.next is None:
                node.next = Node(data)
                return
            node = node.next

    def pop(self) -> int | None:
        if self.head is None:
            self.head = None
            return None

        node = self.head
        assert node is not None

        while True:
            if node.next is None:
                return node.data
            node = node.next

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