#include <iostream>
#include <fstream>
#include <vector>
#define NMAX 16005
using namespace std;

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

int n, dp[NMAX], mmax = -1005;
bool viz[NMAX];
vector <int> fii[NMAX];

void dfs (int node) {
	viz[node] = 1;
	for (int i = 0; i < fii[node].size(); ++i) {
		if (!viz[fii[node][i]]) {
			dfs(fii[node][i]);
			dp[node] = max(dp[node], dp[node] + dp[fii[node][i]]);
			if (dp[node] > mmax) {
				mmax = dp[node];
			}
		}
	}
}

int main () 
{
	fin >> n;
	for (int i = 1; i <= n; ++i) {
		fin >> dp[i];
	}
	int x, y;
	for (int i = 1; i < n; ++i) {
		fin >> x >> y;
		fii[x].push_back(y);
		fii[y].push_back(x);
	}
	dfs(1);
	fout << mmax;
	
	return 0;
}