def __init__(self):
    self.keyRange = 769
    self.bucketArray = [Bucket() for i in range(self.keyRange)]

def _hash(self, key):
    return key%self.keyRange

def add(self,key):
    bucketindex = self._hash(key)
    self.bucketArray[bucketindex].insert(key)

def remove(self, key):
    bucketindex = self._hash(key)
    self.bucketArray[bucketindex].delete(key)

def contains(self,key):
    bucketIndex = self._hash(key)
    self.bucketArray[bucketIndex].exists(key)

def __init__(self, val, nextnode=None):
    self.val = val
    self.nextnode = nextnode

def __init__(self):
    self.head = Node(0)

def add(self, newValue):
    if not self.exists(newValue):
        newNode = Node(newValue, self.head.next)
    self.head.next = newNode

def delete(self, val):
    prev = self.head
    curr = self.head.next
    while curr:
        if curr.val==val:
            prev.nextnode = curr.nextnode
            return
        prev = curr
        curr = curr.nextnode

def exists(self,val):
    curr = self.head.nextnode
    while curr:
        if curr.val==val:
            return True
        curr = curr.nextnode
    return False