#include <fstream.h>
#define N 16100
ifstream fin("asmax.in");
ofstream fout("asmax.out");
struct nod {int info;nod *urm;};
int n,tati[N],radacina,viz[N];
nod *fii[N],*q;
long long s[N],v[N];
void citire()
{
fin>>n;
int i;
for(i=1;i<=n;i++)
	{
	fin>>v[i];
	tati[i]=0;
	}
int a,b;
for(i=1;i<n;i++)
	{
	viz[i]=0;
	fin>>a>>b;
	q=new nod;
	q->info=b;
	q->urm=fii[a];
	fii[a]=q;
	tati[b]=a;
	}
for(i=1;i<=n;i++)
if(tati[i]==0)
	{
	radacina=i;
	break;
	}
}
int max(int a)
{
if(a>0) return a;
return 0;
}

void progdin(int k)
{
nod *p;
p=fii[k];
while (p)
 {if(!viz[p->info])
	{
	viz[p->info]=1;
	progdin(p->info);
    if(v[p->info]>0)
	v[k]=v[k]+s[p->info];
	viz[p->info]=0;
    }
	p=p->urm;

	

 }

}
int main()
{
int max,i,j;
nod *p;
citire();
viz[radacina]=1;
progdin(radacina);
max=-16000000;
for(i=1;i<=n;i++)
if (max<s[i])
max=s[i];
fout<<max<<'\n';
return 0;
}