#include <iostream>
#include <vector>
#include <cmath>
#include <fstream>
using namespace std;
ifstream in("asmax.in");
ofstream out("asmax.out");

void DFS(int nod, vector< vector<int> > &Best, vector< vector<int> > &List, vector<int> &Cost, int p)
{
    Best[nod][1] = Cost[nod];

    for (int i = 0; i < List[nod].size(); i++)
    {
        if (List[nod][i] == p)
            continue;

        DFS(List[nod][i], Best, List, Cost, nod);

        Best[nod][1] += max(Best[ List[nod][i] ][1], 0);
        Best[nod][0] = max(Best[ List[nod][i] ][0], Best[nod][0]);
    }

    Best[nod][0] = max(Best[nod][0], 0);
    Best[nod][0] = max(Best[nod][0], Best[nod][1]);
}
int main()
{
    int n;
    in>> n;

    vector<int> Cost(n);
    vector< vector<int> > v(n);

    for (int i = 0; i < n; i++)
        in>> Cost[i];

    for (int i = 0; i < n - 1; i++)
    {
        int a, b;
        in>> a >> b; a--; b--;

        v[a].push_back(b);
        v[b].push_back(a);
    }

    vector< vector<int> > Best(n, vector<int> (2, 0));
    DFS(0, Best, v, Cost, -1);

    out<< Best[0][0];
    return 0;
}