GATE CS 2025 Set 2 Q49 — Graph Traversals (BFS, DFS)

Consider the following algorithm someAlgo that takes an undirected graph $G$ as input.                                                                                                                  someAlgo (G)

1. Let $v$ be any vertex in $G$. Run BFS on $G$ starting at $v$. Let $u$ be a vertex in $G$ at maximum distance from $v$ as given by the BFS.
2. Run BFS on $G$ again with $u$ as the starting vertex. Let $z$ be the vertex at maximum distance from $u$ as given by the BFS.
3. Output the distance between $u$ and $z$ in $G$.

The output of someAlgo ( $T$ ) for the tree shown in the given figure is ___________. (Answer in integer)