#include <fstream>
#include <vector>

using namespace std;

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

const int oo = 1e9;

int n;
vector<int> d, cost;
vector<vector<int> > v;
vector<bool> viz;
int mx = -oo;

inline void read() {
    fin >> n;

    cost = vector<int>(n + 1);
    d = vector<int>(n + 1, -oo);
    v = vector<vector<int> >(n + 1);
    viz = vector<bool>(n + 1);

    for (int i = 1; i <= n; ++i)
        fin >> cost[i];

    int x, y;
    for (int i = 1; i < n; ++i) {
        fin >> x >> y;
        v[x].push_back(y);
        v[y].push_back(x);
    }
}

void dfs(int node) {
    viz[node] = 1;
    d[node] = cost[node];
    for (const int& newNode: v[node]) {
        if (!viz[newNode]) {
            dfs(newNode);
            d[node] = max(d[node], d[newNode] + d[node]);
        }
    }
    mx = max(mx, d[node]);
}

int main()
{
    read();
    dfs(1);

    fout << mx;
    fin.close();
    fout.close();
    return 0;
}