Paths on the tree

bobo has a tree, whose vertices are conveniently labeled by 1,2,…,n.

There are m paths on the tree. bobo would like to pick some paths while any two paths do not share common vertices.

Find the maximum number of paths bobo can pick.

The input consists of several tests. For each tests:

The first line contains n,m (1≤n,m≤10⁵). Each of the following (n - 1) lines contain 2 integers a_i,b_i denoting an edge between vertices a_i and b_i (1≤a_i,b_i≤n). Each of the following m lines contain 2 integers u_i,v_i denoting a path between vertices u_i and v_i (1≤u_i,v_i≤n).

For each tests:

A single integer, the maximum number of paths.

3 2
1 2
1 3
1 2
1 3
7 3
1 2
1 3
2 4
2 5
3 6
3 7
2 3
4 5
6 7

1
2

Xiaoxu Guo (ftiasch)

2014 Multi-University Training Contest 5