#include<stdio.h>
#define DIM 16005
struct nod
{
    int x;
    nod *urm;
} *lst[DIM];
int b[DIM],v[DIM];
void add (int a,int b)
{
    nod *p=new nod;
    p->x=b;
    p->urm=lst[a];
    lst[a]=p;
}
void df (int k)
{
    v[k]=1;
    for(nod *p=lst[k];p;p=p->urm)
        if(v[p->x]==0)
        {
            df(p->x);
            if(b[p->x]>0) 
                b[k] += b[p->x];
        }
}
int main ()
{
    freopen("asmax.in","r",stdin);
    freopen("asmax.out","w",stdout);
    int i,x,y,n;
    scanf("%d",&n);
    for(i=1;i<=n;++i)
        scanf("%d",&b[i]);
    for(i=1;i<n;++i)
        scanf("%d%d",&x,&y),add(x,y),add(y,x);
    df(1);
    int max=-2000000000;
    for(i=1;i<=n;++i)
        if(max<b[i])
            max=b[i];
    printf("%d",max);
    return 0;
}