#include <bits/stdc++.h>

using namespace std;

const int N = 100010;

vector <int> g[N];
int n, a[N], f[N][2];

void go (int u = 1) {
  for (int v : g[u]) {
    g[v].erase(find(g[v].begin(), g[v].end(), u));
    go(v);
  }
  if (g[u].empty()) {
    f[u][0] = a[u], f[u][1] = a[u] ^ 1;
    return;
  }
  vector <int> oth;
  for (int v : g[u]) oth.emplace_back(f[v][1] - f[v][0]);
  sort(oth.rbegin(), oth.rend());
  {
    int total = 0;
    for (int v : g[u]) total += f[v][0];
    f[u][0] = total;
    for (int i = 2; i <= oth.size(); i += 2) {
      total += oth[i - 1] + oth[i - 2];
      f[u][0] = max(f[u][0], total);
    }
    f[u][0] += a[u];
  }
  {
    int total = 0;
    for (int v : g[u]) total += f[v][0];
    total += oth[0], f[u][1] = total;
    for (int i = 3; i <= oth.size(); i += 2) {
      total += oth[i - 1] + oth[i - 2];
      f[u][1] = max(f[u][1], total);
    }
    f[u][1] += a[u] ^ 1;
  }
}

int main() {
  cin >> n;
  for (int i = 1; i <= n; ++i) {
    scanf("%d", a + i);
  }
  for (int i = 1, u, v; i < n; ++i) {
    scanf("%d %d", &u, &v);
    g[u].emplace_back(v);
    g[v].emplace_back(u);
  }
  go();
  cout << max(f[1][0], f[1][1]) << '\n';
  return 0; 
}