class LRUCache:
    class Node:
        def __init__(self, key, value):
            self.key = key
            self.value = value
            self.prev = None
            self.next = None

    def __init__(self, capacity: int):
        self.capacity = capacity
        self.cache = {}
        self.head = self.Node(0, 0)
        self.tail = self.Node(0, 0)
        self.head.next = self.tail
        self.tail.prev = self.head

    def _remove(self, node):
        prev = node.prev
        nxt = node.next
        prev.next = nxt
        nxt.prev = prev

    def _add_to_end(self, node):
        prev = self.tail.prev
        prev.next = node
        node.prev = prev
        node.next = self.tail
        self.tail.prev = node

    def get(self, key: int) -> int:
        if key not in self.cache:
            return -1
        node = self.cache[key]
        self._remove(node)
        self._add_to_end(node)
        return node.value

    def put(self, key: int, value: int) -> None:
        if self.capacity == 0:
            return
        if key in self.cache:
            node = self.cache[key]
            node.value = value
            self._remove(node)
            self._add_to_end(node)
        else:
            if len(self.cache) == self.capacity:
                lru = self.head.next
                self._remove(lru)
                del self.cache[lru.key]
            node = self.Node(key, value)
            self.cache[key] = node
            self._add_to_end(node)