CF1637F.Towers

普及/提高-

通过率：0%

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题目描述

You are given a tree with $n$ vertices numbered from $1$ to $n$ . The height of the $i$ -th vertex is $h_i$ . You can place any number of towers into vertices, for each tower you can choose which vertex to put it in, as well as choose its efficiency. Setting up a tower with efficiency $e$ costs $e$ coins, where $e > 0$ .

It is considered that a vertex $x$ gets a signal if for some pair of towers at the vertices $u$ and $v$ ( $u \neq v$ , but it is allowed that $x = u$ or $x = v$ ) with efficiencies $e_u$ and $e_v$ , respectively, it is satisfied that $\min(e_u, e_v) \geq h_x$ and $x$ lies on the path between $u$ and $v$ .

Find the minimum number of coins required to set up towers so that you can get a signal at all vertices.

输入格式

The first line contains an integer $n$ ( $2 \le n \le 200\,000$ ) — the number of vertices in the tree.

The second line contains $n$ integers $h_i$ ( $1 \le h_i \le 10^9$ ) — the heights of the vertices.

Each of the next $n - 1$ lines contain a pair of numbers $v_i, u_i$ ( $1 \le v_i, u_i \le n$ ) — an edge of the tree. It is guaranteed that the given edges form a tree.

输出格式

Print one integer — the minimum required number of coins.

输入输出样例

输入#1
```
3
1 2 1
1 2
2 3
```
输出#1
```
4
```
输入#2
```
5
1 3 3 1 3
1 3
5 4
4 3
2 3
```
输出#2
```
7
```
输入#3
```
2
6 1
1 2
```
输出#3
```
12
```

说明/提示

In the first test case it's optimal to install two towers with efficiencies $2$ at vertices $1$ and $3$ .

In the second test case it's optimal to install a tower with efficiency $1$ at vertex $1$ and two towers with efficiencies $3$ at vertices $2$ and $5$ .

In the third test case it's optimal to install two towers with efficiencies $6$ at vertices $1$ and $2$ .

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