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

ifstream in("asmax.in");
ofstream out("asmax.out");

const int N=16006;
vector<int> a[N];
int use[N];
int v[N];
int smax,s;

void dfs(int x)
{
	use[x]=1;
	for(vector<int> :: iterator i=a[x].begin(); i!=a[x].end();i++)
	{
		if(!use[*i])
		{
			dfs(*i);
			if(v[*i]>0)
				v[x]+=v[*i];
		}
	}
}
			

int main()
{
	int n,i,x,y;
	in>>n;
	for(i=1;i<=n;i++)
		in>>v[i];
	for(i=1;i<=n-1;i++)
	{
		in>>x>>y;
		a[x].push_back(y);
		a[y].push_back(x);
	}
	dfs(1);
	for(i=1;i<=n;i++)
		if(v[i]>smax)
			smax=v[i];
	out<<smax;
}