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

using namespace std;

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

void DFS(int &nod_curent, vector <int>& viz, vector <int>& val, vector <vector <int>>& lista_vecini) {
    viz[nod_curent] = 1;
    for (int i = 0; i < lista_vecini[nod_curent].size(); i++)
        if (viz[lista_vecini[nod_curent][i]] == 0) {
            DFS(lista_vecini[nod_curent][i], viz, val, lista_vecini);
            if (val[lista_vecini[nod_curent][i]] > 0)
                val[nod_curent] = val[nod_curent] + val[lista_vecini[nod_curent][i]];
        }
}

int main() {
    int n;
    in >> n;
    vector <int> val(n + 1, 0);
    for (int i = 1; i <= n; i++)
        in >> val[i];
    vector <vector <int>> v;
    v.resize(n + 1);
    for (int i = 1; i <= n - 1; i++) {
        int x, y;
        in >> x >> y;
        v[x].push_back(y);
        v[y].push_back(x);
    }
    int nod_curent = 1;
    vector <int> viz(n + 1, 0);
    DFS(nod_curent, viz, val, v);
    out << val[1];
    in.close();
    out.close();
    return 0;
}