#include<iostream>
#include<fstream>
#include<vector>
using namespace std;

#define NMAX 16001
#define INF 1<<30

vector <int> v[NMAX];
int c[NMAX],d[NMAX],viz[NMAX];

void dfs(int nod)
{
	d[nod]=c[nod];
	viz[nod]=1;
	for(vector <int> :: iterator it=v[nod].begin();it!=v[nod].end();it++)
		if(viz[*it]==0) {
			dfs(*it);
			if(d[*it]>=0)
				d[nod]=d[nod]+d[*it];
		}
}

int main ()
{
	int n,i,x,y,sol;
	ifstream f("asmax.in");
	ofstream g("asmax.out");
	f>>n;
	for(i=1;i<=n;i++)
		f>>c[i];
	for(i=1;i<=n-1;i++) {
		f>>x>>y;
		v[x].push_back(y);
		v[y].push_back(x);
	}
	f.close();
	dfs(1);
	sol=-INF;
	for(i=1;i<=n;i++)
		sol=max(sol,d[i]);
	g<<sol;
	g.close();
	return 0;
}