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

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

int n;
bool viz[16001];

vector<int>graf[16001];
vector<int>cost;
int suma[100001];

int parcurgere(int nod){

    if( viz[nod] )
        return suma[nod];

    viz[nod] = true;
    int pret = cost[nod];
    for(int i = 0; i < graf[nod].size(); ++i){
        int vecin = graf[nod][i];
        if(viz[vecin] == false){
            int x = parcurgere(vecin);
            if(x >= 0)
                pret = pret + x;
        }

    }
    suma[nod] = pret;
    return pret;

}

int main()
{
    ///citirea costurilor, aflarea costului maxim si numarul de costuri pozitive
    in>>n;
    cost.push_back(0);
    int nr_poz = 0, cost_max = -1001;
    for(int i = 1; i<=n; ++i){
        int c; in>>c;
        cost.push_back(c);
        if(c>=-1)
            ++nr_poz;
        cost_max = max(cost_max, c);
    }

    /// citirea grafului neorientat
    for(int i = 1; i<n; ++i){
        int a, b; in>>a>>b;
        graf[a].push_back(b);
        graf[b].push_back(a);
    }

    if(nr_poz <=1){
        out<<cost_max;
        return 0;
    }

    int a = parcurgere(1);

    int smax = -1001;
    for(int i = 1; i <= n; ++i){
        smax = max(smax, suma[i]);
    }
    out<<smax;

    in.close();
    out.close();
    return 0;
}