#include <iostream>
#include <fstream>
#include <climits>

#define INF INT_MAX/2
 
using namespace std;
short a[16001][16001];
int n,v[16001],viz[16001],m;
ofstream fout("asmax.out");
 
void citire()
{
	ifstream fin("asmax.in");
	fin>>n;
	for(int i=1;i<=n;i++)
		fin>>v[i];
	for(int i=1;i<n;i++)
	{
		int x,y;
		fin>>x>>y;
		a[x][y]=a[y][x]=1;
	}
}
int max (int a,int b)
{
	if(a>b) return a;
	return b;
}
int det(int vf)
{
	int sum=-INF;
	for(int i=1;i<=n;i++)
		if(a[vf][i] && viz[i]==0)
		{
			viz[i]=1;
			int p=det(i);
			if(sum>=0 && p>0)
				sum+=p;
			else if(p>sum)
				sum=p;
		}
	v[vf]=max(v[vf],v[vf]+sum);
	return v[vf];
}

int main()
{
	citire();
	viz[1]=1;
	det(1);
	m=-INF;
	for(int i=1;i<=n;i++)
		if(v[i]>m) m=v[i];
	fout<<m;
	return 0;
}