java

class BinaryTree
{
    private BinaryTree leftSubtree;
    private int label;
    private BinaryTree rightSubtree;

    BinaryTree(BinaryTree left, int val, BinaryTree right)
    {
        leftSubtree = left;
        label = val;
        rightSubtree = right;
    }

    public int getLabel()
    {
        return label;
    }

    public boolean isInOrder()
    {
        return leftSubtree.getLabel() < label
        && label < rightSubtree.getLabel();
    }
    public static void main(String[] args)
    {
        BinaryTree bt = new BinaryTree(null, 5, null);
        bt = new BinaryTree(bt, 7, null);
        System.out.println(bt.isInOrder());
    }
}