#include <cstdio>
#include <vector>

using namespace std;

#define FIN "asmax.in"
#define FOUT "asmax.out"

#define N 16001
#define INF 1000000000

int n, v[N], s[N], a[N];

vector <int> m[N];

int max(int a, int b)
{
    return a > b ? a : b;
}

void DFS(int x)
{
	int i;

	s[x] = v[x];
    a[x] = 1;

	for (i = 0; i < m[x].size(); ++ i)
        if (!a[m[x][i]])
        {
            DFS(m[x][i]);

            if (s[m[x][i]] > 0)
                s[x] += s[m[x][i]];
        }
}

int main()
{
    int i, x, y, smax;

    freopen(FIN, "r", stdin);
    freopen(FOUT, "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);

        m[x].push_back(y);
        m[y].push_back(x);
    }

    DFS(1);

    for (i = 1, smax = - INF; i <= n; ++ i)
        smax = max(smax, s[i]);

    printf("%d\n", smax);
}