Luogu_P_1352.cpp

#include <bits/extc++.h>
using namespace std;
namespace pbds = __gnu_pbds;
using ui = unsigned int;
using tree = vector<vector<size_t>>;
void dfs(vector<int> const& r, tree const& t, vector<pair<int, int>>& f,
         size_t const& p) {
  f[p].first = r[p], f[p].second = 0;
  for (size_t const& i : t[p]) {
    dfs(r, t, f, i);
    f[p].first += f[i].second, f[p].second += max(f[i].first, f[i].second);
  }
}
int main(void) {
  ios::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr);
  size_t n;
  cin >> n;
  vector<int> r(n);
  for (int& i : r) cin >> i;
  tree t(n);
  size_t root = 0;
  for (size_t i = 0; i < n; i++) root ^= i;
  for (size_t i = 1; i < n; i++) {
    size_t l, k;
    cin >> l >> k;
    t[--k].push_back(--l);
    root ^= l;
  }
  vector<pair<int, int>> f(n);  // first: 来了    second: 没来
  dfs(r, t, f, root);
  cout << max(f[root].first, f[root].second);
#ifdef debug
  cout.put('\n');
  for (pair<int, int> const& i : f) cout << i.first << ' ' << i.second << '\n';
#endif
  return 0;
}