#include <cstdio>
#include <vector>

using namespace std;

vector<int> g[16001];
int vis[16001];
bool checked[16001];
int v[16001];
int counter = 0;

int dfs(int node)
{
    vis[node] = counter;
    int s = v[node];
    for (unsigned i = 0; i < g[node].size(); i++)
        if (vis[g[node][i]] != counter)
            s += dfs(g[node][i]);
    if (s < 0)
        s = 0;
    else
        checked[node] = 1;
    return s;
}

int main()
{
    FILE *in = fopen("asmax.in", "r");
    FILE *out = fopen("asmax.out", "w");

    int n;
    fscanf(in, "%d", &n);
    int nmax = -2000;
    for (int i = 1; i <= n; ++i)
    {
        fscanf(in, "%d", &v[i]);
        if (v[i] > nmax)
            nmax = v[i];
    }
    for (int x, y, i = 1; i < n; ++i)
    {
        fscanf(in, "%d%d", &x, &y);
        g[x].push_back(y);
        g[y].push_back(x);
    }

    if (nmax <= 0)
    {
        fprintf(out, "%d", nmax);
        return 0;
    }
    int sol = 0;
    for (int i = 1; i <= n; ++i)
        if (v[i] > 0 && !checked[i])
        {
            ++counter;
            int x = dfs(i);
            if (x > sol)
                sol = x;
        }
    fprintf(out, "%d\n", sol);

    return 0;
}