You are given two nodes, p and q. The task is to return their lowest common ancestor (LCA). Both nodes have a reference to their parent node. The tree’s root is not provided; you must use the parent pointers to find the nodes’ common ancestor.

Note: The lowest common ancestor of two nodes, p and q, is the lowest node in the binary tree, with both p and q as descendants.

In a tree, a descendant of a node is any node reachable by following edges downward from that node, including the node itself.

Constraints:

• $-10^4 \leq$Node.data $\leq 10^4$

• The number of nodes in the tree is in the range $[2, 500].$

• All Node.data are unique.

• p != q

• Both p and q are present in the tree.