#include <iostream>
#include <fstream>
#include <vector>
#define Nmax 16005

using namespace std;

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

vector<int>v[Nmax];
int viz[Nmax], dp[Nmax], Smax, val[Nmax], n, x, y;
void dfs(int nod)
{
    viz[nod] = 1;
    for(int i = 0 ;  i < v[nod].size(); i++)
    {
        if(!viz[v[nod][i]])
        {

            dfs(v[nod][i]);
            dp[nod] += max(0, dp[v[nod][i]]);
        }
    }
    dp[nod] += val[nod];
    Smax = max(Smax, dp[nod]);
}
int main()
{
    fin >> n;
    for(int i = 1; i <= n; i++)
        fin >> val[i];
    for(int i = 1; i <= n - 1; i++)
    {
        fin >> x >> y;
        v[x].push_back(y);
        v[y].push_back(x);
    }
    dfs(1);
    fout << Smax;
    return 0;
}