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


class LRUCache:
    def __init__(self, capacity: int):
        self.cap = capacity
        self.cache = {}
        self.left = Node(0, 0)
        self.right = Node(0, 0)
        self.left.next = self.right
        self.right.prev = self.left

    def remove(self, node):
        p, n = node.prev, node.next
        p.next = n
        n.prev = p

    def insert(self, node):
        p, n = self.right.prev, self.right
        p.next = node
        node.prev = p
        node.next = n
        n.prev = node

    def get(self, key: int) -> int:
        if key not in self.cache:
            return -1
        node = self.cache[key]
        self.remove(node)
        self.insert(node)
        return node.val

    def put(self, key: int, value: int) -> None:
        if key in self.cache:
            self.remove(self.cache[key])
        node = Node(key, value)
        self.cache[key] = node
        self.insert(node)
        if len(self.cache) > self.cap:
            lru = self.left.next
            self.remove(lru)
            del self.cache[lru.key]


if __name__ == "__main__":
    lru = LRUCache(2)
    lru.put(1, 1)
    lru.put(2, 2)
    print(lru.get(1))
    lru.put(3, 3)
    print(lru.get(2))
    lru.put(4, 4)
    print(lru.get(1))
    print(lru.get(3))
    print(lru.get(4))