#include<bits/stdc++.h>

using namespace std;

#define fi first
#define se second
#define mp make_pair
#define pb push_back
#define pf push_front
#define LC k<<1
#define RC k<<1|1
#define IO cin.sync_with_stdio(false); cin.tie(0); cout.tie(0);
#define all(x) (x).begin(), (x).end()
#define SZ(x) ((int)(x).size())
#define rep(i,a,n) for (int i = a; i < n; i++)
#define repn(i,a,n) for (int i = a; i <= n; i++)
#define per(i,a,n) for (int i = (n) - 1; i >= a; i--)
#define pern(i,a,n) for (int i = n; i >= a; i--)

typedef long long LL;
typedef long double LD;
typedef unsigned long long ull;
typedef pair<int, int> PII;
typedef pair<int, LL> PIL;
typedef pair<LL, int> PLI;
typedef pair<double, double> PDD;
typedef pair<ull, ull> PUU;
typedef pair<LL, LL> PLL;

const int N = 110000;
const int M = 1100000;
const int mod = 1e9+7;
const int inf = (int)1e9;
const LL INF = 1e18;
const double eps = 1e-9;

mt19937_64 Rand((unsigned long long)new char);
#define rand Rand

int n, col[N], dp[N][2];
vector<int> g[N];
void dfs(int x, int fa) {
	if (g[x].size() == 1 && x != 1) {	
		dp[x][0] = col[x];
		dp[x][1] = col[x] ^ 1;
		return;
	}
	int n0 = 0, n1 = -inf, cnt = 0;
	for (auto y: g[x]) {
		if (y != fa) {
			dfs(y, x);
			if (cnt == 0) n0 = dp[y][0], n1 = dp[y][1];
			else {
				int cn0 = max(n0 + dp[y][0], n1 + dp[y][1]);
				int cn1 = max(n0 + dp[y][1], n1 + dp[y][0]);
				n0 = cn0, n1 = cn1;
			}
			cnt++;
		}
	}
	dp[x][0] = n0 + col[x], dp[x][1] = n1 + (col[x] ^ 1);
}
int main() {
	IO;
	cin >> n;
	repn(i, 1, n) cin >> col[i];
	rep(i, 1, n) {
		int x, y;
		cin >> x >> y;
		g[x].pb(y), g[y].pb(x);
	}
	dfs(1, 0);
	cout << max(dp[1][0], dp[1][1]) << "\n";
	return 0;
}