Given a cactus graph, compute the maximum distance between two vertices.

Constraints

~1 \le N \le 5 \cdot 10^4~

~0 \le M \le 10^4~

~2 \le K_i \le 10^3~

Input Specification

The first line contains two space-separated integers, ~N~ and ~M~. There are ~N~ vertices labeled from ~1~ to ~N~.

~M~ lines follow. Each line starts with an integer ~K_i~, followed by ~K_i~ space-separated integers. Adjacent integers in each line are connected with an edge. The graph is guaranteed to be a connected cactus.

Output Specification

Output the diameter of the graph.

Sample Input

15 3
9 1 2 3 4 5 6 7 8 3
7 2 9 10 11 12 13 10
5 2 14 9 15 10

Sample Output

8