#include <iostream>
#include <fstream>
#include <algorithm>
#include <vector>

using namespace std;

int n, v[16005];

bool vis[16005];
vector<int> muchii[16005];

int vmax = -16000005;

int go(int nod)
{
	vis[nod] = true;
	int s = v[nod];
	for(unsigned i = 0; i < muchii[nod].size(); ++i)
	{
		if(!vis[muchii[nod][i]])
		{
			int ret = go(muchii[nod][i]);
			if(ret > 0)
			{
				vmax = max(vmax, ret);
				s += ret;
			}
		}
	}
	
	vmax = max(vmax, s);
	
	return s;
}

int main()
{
	ifstream in("asmax.in");
	ofstream out("asmax.out");
	
	in >> n;
	for(int i = 0; i < n; ++i)
		in >> v[i];
	for(int i = 0; i < n-1; ++i)	
	{	
		int a, b;
		in >> a >> b;
		--a, --b;
		muchii[a].push_back(b);
		muchii[b].push_back(a);
	}
	
	int root = 0;
	go(root);
	out << vmax;
	return 0;
}