#include<bits/stdc++.h>
#define int long long
using namespace std;
const int INF = 1e16 + 7;
struct edge{
	int to,nxt;
}e[200010];
int n,nE = 0;
int hd[100010];
int a[100010],f[100010][2];
void add(int u,int v){
	e[++nE] = (edge){v,hd[u]};
	hd[u] = nE;
}
void dfs(int u,int fa){
	int g[2];
	g[0] = 0,g[1] = -INF;
	bool fl = 0;
	for(int i = hd[u]; i; i = e[i].nxt){
		int v = e[i].to;
		if(v == fa) continue;
		dfs(v,u);
		fl = 1;
		int g0 = g[0],g1 = g[1];
		g[0] = max(g0 + f[v][0],g1 + f[v][1]),g[1] = max(g0 + f[v][1],g1 + f[v][0]);
	}
	if(a[u]) f[u][0] = g[0] + 1,f[u][1] = g[1];
	else f[u][0] = g[0],f[u][1] = g[1] + 1;
	if(!fl){
		if(a[u]) f[u][0] = 1,f[u][1] = 0;
		else f[u][0] = 0,f[u][1] = 1;
	}
}
signed main(){
	scanf("%lld",&n);
	for(int i = 1; i <= n; i++) scanf("%lld",&a[i]);
	for(int i = 1,u,v; i < n; i++){
		scanf("%lld %lld",&u,&v);
		add(u,v),add(v,u);
	}
	dfs(1,0);
	printf("%lld\n",max(f[1][0],f[1][1]));
	return 0;
}