多校 hdu 5325

Crazy Bobo

Time Limit: 6000/3000 MS (Java/Others)    Memory Limit: 131072/65536 K (Java/Others)
Total Submission(s): 1308    Accepted Submission(s): 400

Problem Description

Bobo has a tree,whose vertices are conveniently labeled by 1,2,...,n.Each node has a weight  wi. All the weights are distrinct.
A set with m nodes  v1,v2,...,vm is a Bobo Set if:
- The subgraph of his tree induced by this set is connected.
- After we sort these nodes in set by their weights in ascending order,we get  u1,u2,...,um,(that is, wui<wui+1 for i from 1 to m-1).For any node  x in the path from  ui to  ui+1(excluding  ui and  ui+1),should satisfy  wx<wui.
Your task is to find the maximum size of Bobo Set in a given tree.

 

Input

The input consists of several tests. For each tests:
The first line contains a integer n ( 1≤n≤500000). Then following a line contains n integers  w1,w2,...,wn ( 1≤wi≤109,all the  wi is distrinct).Each of the following n-1 lines contain 2 integers  ai and  bi,denoting an edge between vertices  ai and  bi ( 1≤ai,bi≤n).
The sum of n is not bigger than 800000.

 

Output

For each test output one line contains a integer,denoting the maximum size of Bobo Set.

 

Sample Input

7 3 30 350 100 200 300 400 1 2 2 3 3 4 4 5 5 6 6 7

 

Sample Output

5

 

Author

ZSTU

 

Source

2015 Multi-University Training Contest 3

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