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

using namespace std;

void dfs(int x);

int n, v[16001], s[16001];
vector<int> c[16001];
vector<bool> b(16001);
int res;

int main()
{
	ifstream fin("asmax.in");
	ofstream fout("asmax.out");

	fin >> n;
	for (int i = 1; i <= n; ++i)
		fin >> v[i];
	for (int i = 1, n1, n2; i < n; ++i)
	{
		fin >> n1 >> n2;
		c[n1].push_back(n2);
		c[n2].push_back(n1);
	}

	dfs(1);

	for (int i = 1; i <= n; ++i)
		res = max(res, s[i]);
	fout << res;

	fin.close();
	fout.close();
}

void dfs(int x)
{
	b[x] = true;
	s[x] = v[x];

	for (vector<int>::iterator it = c[x].begin(); it != c[x].end(); ++it)
		if (!b[*it])
		{
			dfs(*it);
			s[x] = max(s[x], s[x] + s[*it]);
		}
}