#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][++a[x][0]]=y;
		a[y][++a[y][0]]=x;
	}
}
void det(int vf)
{
	viz[vf]=1;
	for(int i=1;i<=a[vf][0];++i)
		if(viz[a[vf][i]]==0)
		{
			det(a[vf][i]);
			if(v[a[vf][i]]>0)
				v[vf]+=v[a[vf][i]];
		}
}

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