#include <bits/stdc++.h>

using namespace std;

typedef long long ll;
template<class T> void check_min(T &a, const T &b){ a = (a < b) ? a : b; }
template<class T> void check_max(T &a, const T &b){ a = (a > b) ? a : b; }
#define all(x) (x).begin(), (x).end()

const int N = 1e5 + 3;
const int INF = 1e9;

int n, a[N];
vector<int> adj[N];

int dp[N][2];

void solve(int u, int p = -1){
    vector<int> v;
    for(int to: adj[u]){
        if(to == p) continue;
        v.push_back(to);
        solve(to, u);
    }

    static int dp2[N][2];
    for(int i = 0; i <= v.size(); ++i){
        if(i == 0){
            dp2[i][0] = 0;
            dp2[i][1] = -INF;
            continue;
        }
        int x = v[i - 1];
        dp2[i][0] = max(dp[x][0] + dp2[i - 1][0], dp[x][1] + dp2[i - 1][1]);
        dp2[i][1] = max(dp[x][0] + dp2[i - 1][1], dp[x][1] + dp2[i - 1][0]);
    }

    if(v.size() == 0){
        dp[u][0] = a[u];
        dp[u][1] = !a[u];
    }
    else{
        dp[u][0] = dp2[v.size()][0] + a[u];
        dp[u][1] = dp2[v.size()][1] + !a[u];
    }
}

int main(){
    ios::sync_with_stdio(false);
    cin.tie(NULL);

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

    solve(1);

    cout << max(dp[1][0], dp[1][1]) << "\n";
}