#include <cstdio>
#include <vector>
#define N 16003
using namespace std;

vector <int> nod[N];
int sol[N],ok[N];

void df(int a)
{
	ok[a]=1;
	while (!nod[a].empty())
	{
		if (!ok[nod[a].back()])
		{
			df(nod[a].back());
			if (sol[nod[a].back()]>0) sol[a]+=sol[nod[a].back()];
		}
		nod[a].pop_back();
	}
}
		

int main()
{
	int n,i,mx=-1000;
	freopen("asmax.in","r",stdin);
	freopen("asmax.out","w",stdout);
	scanf("%d",&n);
	for (i=1;i<=n;++i)
		scanf("%d",&sol[i]);
	for (i=1;i<n;++i)
		{
			int a,b; 
			scanf("%d %d",&a,&b);
			nod[a].push_back(b);nod[b].push_back(a);
		}
	df(1);
	for (i=1;i<=n;++i)
		if (sol[i]>mx) mx=sol[i];
	printf("%d\n",mx);
	return 0;
}