#include<bits/stdc++.h>

using namespace std;

int const maxn = 1e5 + 5;
vector < int > g[maxn];
int dp[maxn][2], f[2], a[maxn];

void dfs(int v, int p) {
    int child = 0;
    for (auto u : g[v]) {
        if (u != p) dfs(u, v), child++;
    }
    if (!child) {
        dp[v][0] = a[v], dp[v][1] = !a[v];
        return;
    }
    dp[v][1] = -maxn;
    for (auto u : g[v]) {
        if (u == p) continue;
        f[0] = -maxn, f[1] = -maxn;
        for (int lst = 0; lst <= 1; lst++) {
            for (int cur = 0; cur <= 1; cur++) {
                f[lst^cur] = max(f[lst^cur], dp[v][lst] + dp[u][cur]);
            }
        }
        dp[v][0] = f[0], dp[v][1] = f[1];
    }
    dp[v][0] += a[v], dp[v][1] += !a[v];
}

main() {
#ifdef HOME
    freopen("input.txt", "r", stdin);
#endif // HOME
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    int n, u, v;
    cin >> n;
    for (int i = 1; i <= n; i++) cin >> a[i];
    for (int i = 1; i < n; i++) {
        cin >> u >> v;
        g[u].push_back(v);
        g[v].push_back(u);
    }
    dfs(1, 0);
    cout << max(dp[1][0], dp[1][1]) << '\n';
    return 0;
}