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

using namespace std;
vector < int > cost_subarbori;
void vizitat( vector < vector < int > > &vecini, vector < int > &culoare, vector < int > &d, vector < int > &f, int u, int &timp, vector < int > costuri ){
    culoare[u] = 1;
    timp++;
    d[u] = timp;
    cost_subarbori[u] = costuri[u];
    for( int i = 0; i < vecini[u].size(); i++ ){
        if( culoare[ vecini[u][i] ] == 0 ){
            vizitat(vecini,culoare,d,f,vecini[u][i],timp,costuri);
            if( cost_subarbori[u] + cost_subarbori[vecini[u][i]] > cost_subarbori[u] ){
                cost_subarbori[u] = cost_subarbori[u] + cost_subarbori[vecini[u][i]];
            }
        }
    }
    culoare[u] = 2;
    timp++;
    f[u] = timp;
}

int main(){
    ifstream fin("asmax.in");
    ofstream fout("asmax.out");
    int nr_noduri, nr_muchii;
    fin >> nr_noduri;
    vector < vector < int > > vecini(nr_noduri+1);
    vector < int > costuri;
    costuri.push_back(999999);
    cost_subarbori.push_back(0);
    for(int i = 0; i < nr_noduri; i++){
        int cost;
        fin >> cost;
        costuri.push_back(cost);
        cost_subarbori.push_back(0);
    }
    for( int i = 0; i < nr_noduri-1; i++ ){
        int intrare, iesire;
        fin >> intrare >> iesire;
        vecini[intrare].push_back(iesire);
        vecini[iesire].push_back(intrare);
    }
    int timp;
    timp = 0;
    vector < int > culoare, d, f;
    for( int i = 0; i <= nr_noduri; i++ ){
        culoare.push_back(0);
        d.push_back(-1);
        f.push_back(-1);
    }
    vizitat(vecini,culoare,d,f,1,timp,costuri);
    int max = cost_subarbori[1];
    for( int i = 1; i < cost_subarbori.size(); i++ ){
        if( max < cost_subarbori[i] ) max = cost_subarbori[i];
    }
    fout << max;
}