#include <cstdio>
#include <vector>

#define NMax 16010
#define Infinit 2000000000

using namespace std;

vector <int> G[NMax];
int N, Value[NMax], Sum[NMax], S=-Infinit;

void Read ()
{
    freopen ("asmax.in", "r", stdin);
    scanf ("%d", &N);
    for (int i=1; i<=N; ++i)
    {
        scanf ("%d", Value+i);
    }
    for (int i=1; i<N; ++i)
    {
        int X, Y;
        scanf ("%d %d", &X, &Y);
        G[X].push_back (Y);
        G[Y].push_back (X);
    }
}

void Write ()
{
    freopen ("asmax.out", "w", stdout);
    printf ("%d\n", S);
}

void DFS (int X, int F)
{
    for (unsigned i=0; i<G[X].size (); ++i)
    {
        int V=G[X][i];
        if(V==F) continue;
        DFS (V, X);
    }
    if (Sum[X]+Value[X]>0)
    {
        Sum[F]+=(Sum[X]+Value[X]);
    }
}

int main()
{
    Read ();
    DFS (1, 0);
    for (int i=1; i<=N; ++i)
    {
        if (Sum[i]+Value[i]>S)
        {
            S=Sum[i]+Value[i];
        }
    }
    Write ();
    return 0;
}