#include <fstream>
#include <vector>
#include <algorithm>
using namespace std;

#define in "asmax.in"
#define out "asmax.out"
#define N 16005
#define INF -(1<<30)

typedef unsigned u;

vector <int> graf[N], v(N, 0), din(N);
vector <bool> d (N, 0);
int n, sol = INF;

void DFS (int x) {
	din[x] = v[x];
	d[x] = 1;
	for (u i = 0; i < graf[x].size(); ++i) {
		if (!d[graf[x][i]]) {
			DFS (graf[x][i]);
			din[x] += max (din[graf[x][i]], 0);
		}
	}
}

int main () {
	ifstream fin (in);
	fin >> n;
	for (int i = 1; i <= n; ++i)
		fin >> v[i];
	for (int i = 0; i < n - 1; ++i) {
		int x, y;
		fin >> x >> y;
		graf[x].push_back (y);
		graf[y].push_back (x);
	}
	fin.close();
	DFS (1);
	for (int i = 1; i <= n; ++i)
		sol = max (din[i], sol);
	ofstream fout (out);
	fout << sol;
	fout.close();
	return 0;
}