#include <iostream>
#include <fstream>
#include <vector>
#include <climits>
using namespace std;

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

int n, down[16001], v[16001];
vector<int> g[16001];
vector<int> max1, max2;
int rez = INT_MIN;

void dfs1 (int nod, int last) {
    down[nod] = v[nod];

    for (auto &i: g[nod])
        if (i != last) {
            dfs1(i, nod);

            if (down[i] > 0)
                down[nod] += down[i];
        }

    rez = max(rez, down[nod]);
}

void dfs2 (int nod, int last, int maxi) {

    rez = max(rez, maxi + down[nod]);

    int sum = maxi;
    vector<bool> b(g[nod].size());

    for (int i = 0; i < g[nod].size(); i++)
        if (g[nod][i] != last && down[g[nod][i]] > 0) {
            sum += down[g[nod][i]];
            b[i] = true;
        }

    sum += v[nod];

    if (sum < 0) {
        for (int i = 0; i < b.size(); i++)
            b[i] = false;
        sum = 0;
    }

    for (int i = 0; i < g[nod].size(); i++)
        if (g[nod][i] != last) {

            if (b[i])
                dfs2(g[nod][i], nod, sum - down[g[nod][i]]);
            else
                dfs2(g[nod][i], nod, sum);
        }
}

int main () {

    fin >> n;

    for (int i = 1; i <= n; i++)
        fin >> v[i];

    for (int i = 1; i < n; i++) {
        int x, y;
        fin >> x >> y;

        g[x].push_back(y);
        g[y].push_back(x);
    }

    dfs1(1, 0);
    dfs2(1, 0, 0);

    fout << rez;

    return 0;
}