import java.util.Set;
/**Interface for a map*/
public interface Map<K,V>{
	public interface Entry<K,V>{
      
		/**Compares the specified object with this entry for equality*/
		public boolean equals(Object o);
		
		/**Returns the key corresponding to 
		 * this entry*/
		public K getKey();
		
		/**Returns the value corresponding to this entry*/
		public V getValue();
		
		/**Returns the hash code value for this map entry*/
		public int hashCode();
		
		/**Replaces the value corresponding to this entry with the specified value*/
		public V setValue(V v);
		
		
	}

	/**return the number of entries in the map*/
	public int size();
	
	/**returns true if this map contains no key-value mappings*/
	public boolean isEmpty(); 
	
	/** Returns the value to which the specific key is mapped, or null  */
	public V get(K key);
	
	/** associates the specific value with the specified key in this map, return old value 
	 * or null if already an entry 
	 * with this key*/
	public V put(K key, V value);
	
	/**Removes the mapping for a key from this map if present*/
	public V remove(K key);
	
	/**return a set containing all the keys stored in map*/
	public Set<K> keys();
	
	/**return a set containing all the values associated with the entries stored*/
	public Set<V> values();
	
	/**return a set containing all the key-value entries*/
	public Set<Map.Entry<K,V>> entries();

}