#include <cassert>
#include <cmath>
#include <cstdint>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <algorithm>
#include <bitset>
#include <complex>
#include <deque>
#include <functional>
#include <iostream>
#include <limits>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <sstream>
#include <string>
#include <unordered_map>
#include <unordered_set>
#include <utility>
#include <vector>

using namespace std;

using Int = long long;

template <class T1, class T2> ostream &operator<<(ostream &os, const pair<T1, T2> &a) { return os << "(" << a.first << ", " << a.second << ")"; };
template <class T> ostream &operator<<(ostream &os, const vector<T> &as) { const int sz = as.size(); os << "["; for (int i = 0; i < sz; ++i) { if (i >= 256) { os << ", ..."; break; } if (i > 0) { os << ", "; } os << as[i]; } return os << "]"; }
template <class T> void pv(T a, T b) { for (T i = a; i != b; ++i) cerr << *i << " "; cerr << endl; }
template <class T> bool chmin(T &t, const T &f) { if (t > f) { t = f; return true; } return false; }
template <class T> bool chmax(T &t, const T &f) { if (t < f) { t = f; return true; } return false; }
#define COLOR(s) ("\x1b[" s "m")


constexpr int INF = 1001001001;

int N;
vector<int> C;
vector<int> A, B;

vector<vector<int>> graph;
int dp[100'010][2];

void dfs(int u, int p) {
  bool leaf = true;
  int crt[2] = {0, -INF};
  for (const int v : graph[u]) if (p != v) {
    leaf = false;
    dfs(v, u);
    int nxt[2] = {-INF, -INF};
    for (int x = 0; x < 2; ++x) for (int y = 0; y < 2; ++y) {
      chmax(nxt[x ^ y], crt[x] + dp[v][y]);
    }
    memcpy(crt, nxt, sizeof(nxt));
  }
  if (leaf) {
    crt[1] = 0;
  }
  crt[C[u] ^ 1] += 1;
  memcpy(dp[u], crt, sizeof(crt));
}

int main() {
  for (; ~scanf("%d", &N); ) {
    C.resize(N);
    for (int u = 0; u < N; ++u) {
      scanf("%d", &C[u]);
    }
    A.resize(N - 1);
    B.resize(N - 1);
    for (int i = 0; i < N - 1; ++i) {
      scanf("%d%d", &A[i], &B[i]);
      --A[i];
      --B[i];
    }
    
    graph.assign(N, {});
    for (int i = 0; i < N - 1; ++i) {
      graph[A[i]].push_back(B[i]);
      graph[B[i]].push_back(A[i]);
    }
    dfs(0, -1);
    const int ans = max(dp[0][0], dp[0][1]);
    printf("%d\n", ans);
  }
  return 0;
}