#include <bits/stdc++.h>
//#include <ext/pb_ds/assoc_container.hpp>
//#include <ext/pb_ds/tree_policy.hpp>
using namespace std;
//using namespace __gnu_pbds;

// #pragma GCC optimize("O3,unroll-loops")
// #pragma GCC target("avx2")
#define watch(x) cout<<(#x)<<"="<<(x)<<'\n'
#define mset(d,val) memset(d,val,sizeof(d))
#define cbug if(DEBUG) cout
#define setp(x) cout<<fixed<<setprecision(x)
#define sz(x) (int)(x).size()
#define all(x) begin(x), end(x)
#define forn(i,a,b) for(int i=(a);i<(b);i++)
#define fore(i,a,b) for(int i=(a);i<=(b);i++)
#define pb push_back
#define F first
#define S second
#define fbo find_by_order
#define ook order_of_key
typedef long long ll;
typedef long double ld;
typedef pair<ll,ll> ii;
typedef vector<ll> vi;
typedef vector<ii> vii;
//template<typename T>
//using pbds = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
void SD(int t=0){ cout<<"PASSED "<<t<<endl; }
ostream& operator<<(ostream &out, ii x){ out<<"("<<x.F<<","<<x.S<<")"; return out; }
template<typename T> void amax(T &a, T b){ a=max(a,b); }
template<typename T> void amin(T &a, T b){ a=min(a,b); }
struct Hash {
    static uint64_t splitmix64(uint64_t x) {
        // http://xorshift.di.unimi.it/splitmix64.c
        x += 0x9e3779b97f4a7c15;
        x = (x ^ (x >> 30)) * 0xbf58476d1ce4e5b9;
        x = (x ^ (x >> 27)) * 0x94d049bb133111eb;
        return x ^ (x >> 31);
    }
    size_t operator()(uint64_t x) const {
        static const uint64_t FIXED_RANDOM = chrono::steady_clock::now().time_since_epoch().count();
        return splitmix64(x + FIXED_RANDOM);
    }
};

const int INF = int(2e7);
const int MOD = 998244353;
const bool DEBUG = 0;
const int MAXN = 100005;
const int LG = 21;

int n;
vector<int> a;
vector<vector<int>> adj;
vector<array<int, 2>> dp;

void dfs(int u, int p)
{
    array<int, 2>& cur = dp[u];
    if (p != -1 && sz(adj[u]) == 1)
    {
        cur = {0, 0};
        cur[a[u] ^ 1]++;
        return;
    }
    cur = {0, -INF};
    for (const auto v : adj[u])
    {
        if (v == p) continue;
        dfs(v, u);
        array<int, 2> cur2 = cur;
        forn(i,0,2)
        {
            forn(j,0,2)
            {
                amax(cur2[i ^ j], cur[i] + dp[v][j]);
            }
        }
        cur = cur2;
    }
    cur[a[u] ^ 1]++;
}

int main()
{
    cin.tie(0)->sync_with_stdio(0);

    cin>>n;
    a.resize(n);
    adj.resize(n);
    dp.resize(n);

    forn(i,0,n) cin>>a[i];
    forn(i,0,n-1)
    {
        int u,v; cin>>u>>v; u--; v--;
        adj[u].pb(v);
        adj[v].pb(u);
    }

    dfs(0, -1);
    cout << max(dp[0][0], dp[0][1]) << '\n';

    return 0;
}