#include <iostream>
#include <fstream>
#include <vector>
#include <algorithm>
#define MAXN 16005

using namespace std;

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

vector<int>graf[MAXN];
bool viz[MAXN];
int n,cost_nod[MAXN],suma,bestsum = -2e9;

void dfs(int nod){
    suma += cost_nod[nod];
    bestsum = max(suma,bestsum);
    if(suma < 0)
        suma = 0;
    viz[nod] = true;
    int curent;
    for(int i = 0; i < graf[nod].size(); i++){
        curent = graf[nod][i];
        if(!viz[curent])
            dfs(curent);
    }
}


int main()
{
    in>>n;
    for(int i = 1; i <= n; i++)
        in>>cost_nod[i];
    for(int i = 1; i <= n-1; i++){
        int x,y;
        in>>x>>y;
        graf[x].push_back(y);
    }
    dfs(1);
    out<<bestsum;
    return 0;
}