#include<bits/stdc++.h>

using namespace std;

int n, cost[16100], x, y, viz[16000],rs;
vector<int> a[16100];
int dfs(int x)
{
	viz[x] = 1;
	int rez=0;
	for (vector<int>::iterator it = a[x].begin(); it != a[x].end(); it++)
	{
		if (!viz[*it])
		{
			rez += dfs(*it);
		}
	}
	rs = max(rs,max(rez + cost[x], max(0,cost[x])));
	return max(rez + cost[x], max(0,cost[x]));
}
int main()
{
	ifstream cin("asmax.in");
	ofstream cout ("asmax.out");
	cin >> n;
	for (int i = 1; i <= n ; i++) cin >> cost[i];
	for (int i = 1; i <= n-1; i++)
	{
		cin >> x >> y;
		a[x].push_back(y);
		a[y].push_back(x);		
	}
	dfs(1);
	cout << rs;
}