#include <cstdio>
#include <algorithm>
#include <cstring>
#include <vector>
#define Nmax 16002
using namespace std;
int n, i, j, x, y, v[Nmax], sol, viz[Nmax], s;
vector < int > V[Nmax];
int dfs(int x, int s)
{
    int S = 0;
    for (int i = 0; i < V[x].size(); ++ i)
        if (!viz[V[x][i]])
    {
        viz[V[x][i]] = 1;
        S = dfs(V[x][i], v[V[x][i]]);
        if (S > 0)
            s += S;
        else viz[V[x][i]] = 0;
    }
    return s;
}
int main()
{
    freopen("asmax.in", "r", stdin);
    freopen("asmax.out", "w", stdout);
    scanf("%d", &n);
    for (i = 1; i <= n; ++ i)
        scanf("%d", &v[i]);
    for (i = 1; i < n; ++ i)
    {
        scanf("%d %d", &x, &y);
        V[x].push_back(y);
        V[y].push_back(x);
    }
    for (i = 1; i <= n; ++ i)
        if (!viz[i])
    {
        viz[i] = 1;
        s = dfs(i, v[i]);
        if (s > sol)
            sol = s;
        memset(viz, 0, sizeof(viz));
    }

    printf("%d", sol);
    return 0;
}