import java.util.ArrayList;

public class BinaryTree {
	private String	   	data;
	private BinaryTree	leftChild;
	private BinaryTree	rightChild;

	// A constructor that takes root data only and
	// makes a tree with no children (i.e., a leaf)
	public BinaryTree(String d) {
		data = d;
		leftChild = null;
		rightChild = null;
	}

	// A constructor that takes root data as well as two subtrees
	// which then become children to this new larger tree.
	public BinaryTree(String d, BinaryTree left, BinaryTree right) {
		data = d;
		leftChild = left;
		rightChild = right;
	}

	// Get methods
	public String getData() { return data; }
	public BinaryTree getLeftChild() { return leftChild; }
	public BinaryTree getRightChild() { return rightChild; }

	// Set methods
	public void setData(String d) { data = d; }
	public void setLeftChild(BinaryTree left) { leftChild = left; }
	public void setRightChild(BinaryTree right) { rightChild = right; }

	// Return the height of the tree
	public int height()  {
	    if (this.leftChild == null) {
	        if (this.rightChild == null)
	        	  return 0;
	        else
	    		  return 1 + this.rightChild.height();
	    }
	    else {
	        if (this.rightChild == null)
	        	  return 1 + this.leftChild.height();
	    	   else
	            return 1 + Math.max(this.leftChild.height(),
	                                this.rightChild.height());
	    }
	}

	// Return all the leaves of the tree
	public ArrayList<String> leafData()  {
		ArrayList<String>	result = new ArrayList<String>();

		if (this.leftChild == null) {
			if (this.rightChild == null)
				result.add(this.data);
			else
				result.addAll(this.rightChild.leafData());
		}
		else {
			result.addAll(this.leftChild.leafData());
			if (this.rightChild != null)
				result.addAll(this.rightChild.leafData());
		}
		return result;
	}
}