#include<bits/stdc++.h>

using namespace std;
#define ll long long
#define pii pair<int, int>
#define ld long double
#define all(a) (a).begin(), (a).end()

const int MAXN = 100100;

vector<int> G[MAXN];
int A[MAXN];
int dp[MAXN][2];

void dfs(int v, int p) {
    for (int i = 0; i < G[v].size(); ++i) {
        if (G[v][i] == p) {
            swap(G[v][i], G[v].back());
            G[v].pop_back();
        }
    }
    if (G[v].empty()) {
        dp[v][0] = A[v];
        dp[v][1] = 1 - A[v];
        return;
    }
    dp[v][0] = 0;
    dp[v][1] = -MAXN;
    for (int u : G[v]) {
        dfs(u, v);
        int dp0 = max(dp[v][0] + dp[u][0], dp[v][1] + dp[u][1]);
        int dp1 = max(dp[v][1] + dp[u][0], dp[v][0] + dp[u][1]);
        dp[v][0] = dp0;
        dp[v][1] = dp1;
    }
    dp[v][0] += A[v];
    dp[v][1] += 1 - A[v];
}

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

    int n;
    cin >> n;
    for (int i = 0; i < n; ++i)
        cin >> A[i];
    for (int i = 1; i < n; ++i) {
        int a, b;
        cin >> a >> b;
        G[a - 1].emplace_back(b - 1);
        G[b - 1].emplace_back(a - 1);
    }
    dfs(0, 0);
    cout << max(dp[0][0], dp[0][1]) << '\n';
    return 0;
}