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

using namespace std;

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

vector<int> val, dp;
vector<vector<int>> g;

void df(int nod, int ant)
{
    dp[nod] = val[nod];
    for (int y : g[nod])
    {
        if (y == ant)
            continue;

        df(y, nod);
        if (dp[y] > 0)
            dp[nod] += dp[y];
    }
}

int main()
{
    int n;
    fin >> n;
    val.resize(n + 1);
    g.resize(n + 1);

    for (int i = 1; i <= n; i++)
        fin >> val[i];
    for (int i = 1; i < n; i++)
    {
        int x, y;
        fin >> x >> y;
        g[x].push_back(y);
        g[y].push_back(x);
    }

    dp.resize(n + 1);
    df(1, 0);

    int mx = -1000;
    for (int i = 1; i <= n; i++)
        mx = max(mx, dp[i]);

    fout << mx;

    return 0;
}