#include <bits/stdc++.h>
using namespace std;

#define int long long

vector<int> dfs(int now, int prv, vector<int> &a, vector<vector<int>> &adj) {
	if (now != 0 && adj[now].size() == 1) {
		return {a[now], 1-a[now]};
	}

	vector<int> ans(2); ans[1] = -998244353;
	for (int u: adj[now]) {
		if (u != prv) {
			auto v = dfs(u, now, a, adj);

			vector<int> nxt(2);
			nxt[0] = max(ans[0] + v[0], ans[1] + v[1]);
			nxt[1] = max(ans[0] + v[1], ans[1] + v[0]);
			swap(ans, nxt);
		}
	}
	ans[0] += a[now]; ans[1] += 1-a[now];

	return ans;
}

signed main() {
	ios::sync_with_stdio(0); cin.tie(0);

	int n; cin >> n;
	vector<int> a(n);
	vector<vector<int>> adj(n);
	for (int i = 0; i < n; i++) {
		cin >> a[i];
	}
	for (int i = 1; i < n; i++) {
		int u, v; cin >> u >> v; u--, v--;
		adj[u].push_back(v);
		adj[v].push_back(u);
	}

	vector<int> ans = dfs(0, 0, a, adj);
	cout << max(ans[0], ans[1]) << '\n';
	
	return 0;
}