#include <bits/stdc++.h>
#define LL long long
#define db double
using namespace std;

const int MAXN = 1e5 + 5;

int n;
int a[MAXN];

int tot, h[MAXN];
struct edge {
	int to, nxt;
} e[MAXN << 1];

void add (int x, int y) {
	e[++tot] = (edge) { y, h[x] }, h[x] = tot;
}

int f[MAXN][2];

void dfs (int x, int fa = 0) {
	f[x][1] = -n;
	for (int u = h[x]; u; u = e[u].nxt)
		if (e[u].to != fa) {
			int i0 = f[x][0], i1 = f[x][1];
			dfs (e[u].to, x);
			f[x][0] = max (i0 + f[e[u].to][0], i1 + f[e[u].to][1]);
			f[x][1] = max (i0 + f[e[u].to][1], i1 + f[e[u].to][0]);
		}
	f[x][1] = max (f[x][1], 0);
	++f[x][a[x] ^ 1];
}

int main() {
	int i,j,k;
	int x, y;
	cin >> n;
	for (i = 1; i <= n; ++i) cin >> a[i];
	for (i = 1; i < n; ++i) 
		cin >> x >> y, add (x, y), add (y, x);
	dfs (1);
	cout << max (f[1][0], f[1][1]);
	return 0;
}