#include <cstdio>

using namespace std;
FILE *in=fopen ("asmax.in","r");
FILE *out=fopen ("asmax.out","w");
const int N=16000;
int n,vf[N],lst[N],urm[N],m,a[N],suma[N],s;
bool viz[N];
void adauga (int x,int y)
{
    vf[++m]=y;
    urm[m]=lst[x];
    lst[x]=m;
}
int rezolvare (int x)
{
    int p,y;
    suma[x]=a[x];
    p=lst[x];
    while (p!=0)
    {
        y=vf[p];
        suma[y]=rezolvare(y);
        if (suma[y]>0)
        s+=suma[y];
        p=urm[p];
    }
    return suma[x];
}
void citire ()
{
    fscanf (in,"%d",&n);
    for (int i=1;i<=n;i++)
    fscanf (in,"%d",&a[i]);
    for (int i=1;i<n;i++)
    {
        int x,y;
        fscanf (in,"%d%d",&x,&y);
        adauga (x,y);
        viz[y]=true;
    }
    int r;
    for (int i=1;i<=n;i++)
    if (!viz[i]) r=i;
    rezolvare(r);
    fprintf (out,"%d",s);
}
int main()
{
    citire();
    return 0;
}