$(8$ pts$)$ Using the binary tree $T$ shown below, answer the following questions:

a$)(5$ pts$)$ Label the binary tree with numbers from the set $\{20,70,40,10,60,50,30\}$ so that it is a legal Binary Search Tree $($BST$).$

b$)(3$ pts $)$ Given the tree $T$ after the labeling of part a$),$ provide an algorithm that outputs the keys of the tree in a sorted order. What is the complexity of your algorithm.