// List

ArrayList<Integer> al= new ArrayList<Integer>();
LinkedList<Integer> ll= new LinkedList<Integer>();

// List 2D

ArrayList<ArrayList<Integer>> al2= new ArrayList<ArrayList<Integer>>();
LinkedList<LinkedList<Integer>> ll2= new LinkedList<LinkedList<Integer>>();
ArrayList<int[]> aa = new ArrayList<int[]>();
LinkedList<long[]> la = new LinkedList<long[]>();

// Adj List, Map, Set

ArrayList<Integer> adj2[] = new ArrayList[1000];
LinkedList<Integer> adj[] = new LinkedList[1000];
HashSet<Integer> hsj[] = new HashSet[1000];
HashMap<Integer,Integer> hmj[] = new HashMap[1000];

// Stack

Stack <Integer> stk = new Stack <Integer>();

// Queue

Queue <Integer> q = new LinkedList<Integer>();

// Deque

ArrayDeque<Integer> ad = new ArrayDeque<Integer>();

// PriorityQueue and Heap

PriorityQueue <Integer> pq = new PriorityQueue<Integer>();
PriorityQueue <Integer> pqr = new PriorityQueue<Integer>(Comparator.reverseOrder());

// Set 

HashSet<Integer> hs = new HashSet<Integer>();
LinkedHashSet<Integer> lhs = new LinkedHashSet<Integer>();
TreeSet<Integer> ts = new TreeSet<Integer>();
TreeSet<Integer> tsr = new TreeSet<Integer>(Comparator.reverseOrder());
SortedSet<Integer> multiset = new TreeSet<>( (i, j) -> i > j ? 1 : -1 );

// Map

HashMap<Integer,Integer> hm = new HashMap<Integer,Integer>();
LinkedHashMap<Integer,Integer> lhm = new LinkedHashMap<Integer,Integer>();
TreeMap<Integer,Integer> tm = new TreeMap<Integer,Integer>();
TreeMap<Integer,Integer> tmr = new TreeMap<Integer,Integer>(Comparator.reverseOrder());
SortedMap< Integer, Integer > multimap = new TreeMap<>( (i, j) -> i > j ? 1 : -1 );

// Hash Table

Hashtable<Integer,Integer> ht = new Hashtable<Integer,Integer>();