#include<bits/stdc++.h>
using namespace std;
using i64 = long long;
using db = double;
constexpr int N = 1e6 + 50, LOGN = 30;
constexpr i64 P = 1e9 + 7, inf = 1e9;

void solve(){
    int n; cin >> n;
    vector<int> a(n);
    for (int i = 0; i < n; i++) cin >> a[i];
    vector<vector<int>> g(n);
    for (int i = 1; i < n; i++) {
        int u, v; cin >> u >> v;
        u--, v--;
        g[u].emplace_back(v);
        g[v].emplace_back(u);
    }
    vector<array<int, 2>> dp(n, {0, -inf});
    auto dfs = [&](auto self, int u, int fa) -> void {
        if (g[u].size() == 1 && u != 0) {
            dp[u][0] = a[u];
            dp[u][1] = !a[u];
            return;
        }
        for (auto v : g[u]) {
            if (v == fa) continue;
            array<int, 2> nx{};
            self(self, v, u);
            nx[0] = max(dp[u][0] + dp[v][0], dp[u][1] + dp[v][1]);
            nx[1] = max(dp[u][1] + dp[v][0], dp[u][0] + dp[v][1]);
            dp[u] = nx;
        }
        dp[u][0] += a[u];
        dp[u][1] += !a[u];
    };
    dfs(dfs, 0, 0);
    cout << max(dp[0][0], dp[0][1]) << " \n";
}

signed main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr), cout.tie(nullptr);
    cout << setprecision(15) << fixed;
    int t = 1;
    //cin >> t;
    while (t--) solve();
    return 0;
}