Tree Diameter

Input

The first line contains an integer n~(1 \le n \le 2 \cdot 10^5) — the number of vertices in the tree. The vertices are numbered from $1$ to $n$.

Each of the following n - 1 lines describes an edge and contains two integers $a$ and b~(1 \le a, b \le n), indicating that there is an edge between vertices $a$ and $b$.

Output

Print one integer — the diameter of the tree.

Examples