#include <stdio.h>

#define DIM 16005

struct nod {int x;
            nod *urm;} *lst[DIM];
int a[DIM],best[DIM],viz[DIM];
int n,max;

void add (int a,int b)
{
    nod *p=new nod;

    p->x=a;
    p->urm=lst[b];
    lst[b]=p;
}

void read ()
{
    int i,x,y;

    scanf ("%d",&n);
    for (i=1; i<=n; ++i)
        scanf ("%d",&a[i]);
    for (i=1; i<n; ++i)
    {
        scanf ("%d%d",&x,&y);
        add (x,y);
        add (y,x);
    }
}

void df (int start)
{
    nod *p;

    viz[start]=1;
    best[start]=a[start];
    for (p=lst[start]; p; p=p->urm)
        if (!viz[p->x])
        {
            df (p->x);
            if (best[p->x]>0)
                best[start]+=best[p->x];
        }
    if (best[start]>max)
        max=best[start];
}

int main ()
{
    freopen ("asmax.in","r",stdin);
    freopen ("asmax.out","w",stdout);

    read ();
    df (1);
    printf ("%d",max);

    return 0;
}