#include <iostream>
#include <fstream>
#include <vector>
#define DIM 20000

using namespace std;

int v[DIM], viz[DIM], i, s[DIM], n, x, y, maxim = -1<<30;
vector <int> L[DIM];

void dfs(int nod)
{
	viz[nod] = 1;
	for (int i = 0; i < L[nod].size(); i++)
	{
		int vec = L[nod][i];
		if (viz[vec] == 0)
		{
			dfs(vec);
			if (v[vec] > 0)
				v[nod] += v[vec];
		}
	}
}

int main()
{
	ifstream f("asmax.in");
	ofstream g("asmax.out");

	f >> n;
	for (i = 1; i <= n; i++)
		f >> v[i];
	for (i = 1; i < n; i++)
	{
		f >> x >> y;
		L[x].push_back(y);
		L[y].push_back(x);
	}
	dfs(1);
	for (i = 1; i <= n; i++)
	{
		if (v[i] > maxim)
			maxim = v[i];
	}
	g << maxim;
	return 0;
}