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

#define lim 16001
#define INF INT_MAX/2
 
using namespace std;
int n,v[16001],viz[16001],m;
vector<int>G[lim];
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;
		G[x].push_back(y);
		G[y].push_back(x);
	}
}
void det(int vf)
{
	viz[vf]=1;
	for(int i=0;i<G[vf].size();++i)
	{
		int v2=G[vf][i];
		if(viz[v2]==0)
		{
			det(v2);
			if(v[v2]>0)
				v[vf]+=v[v2];
		}
	}
}

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;
}