/**
	 * Build a new BHT from an Input Stream.
	 * If the file is bad, it throws CorruptedFileException.
	 * Precondition : the BufferedInputStream must be valid and place just before the beginning of the tree.
	 * Complexity : O(n) with n = the number of nodes.
	 */
	public static BinaryHuffmanTree buildIn (BufferedInputStream in) throws CorruptedFileException {
		try {
			int octet = in.read();
			if (octet == 0) {
				BinaryHuffmanTree noeud = new BinaryHuffmanTree(buildIn(in),buildIn(in));
				return noeud;
			}
			else if (octet == 1) {
				return new BinaryHuffmanTree(in.read());
			}
			else {
				throw new CorruptedFileException ("The tree wasn't well build.", CorruptedFileException.CorruptedType.BadTree);
			}
		}
		catch (IOException ex) {
			throw new CorruptedFileException ("End of file found too early.", CorruptedFileException.CorruptedType.CuttedFile);
		}
	}