#include<bits/stdc++.h>
#define For(i,a,b) for(int i=(a);i<=(b);++i)
#define Rep(i,a,b) for(int i=(a);i>=(b);--i)
using namespace std;
inline int read()
{
	char c=getchar();int x=0;bool f=0;
	for(;!isdigit(c);c=getchar())f^=!(c^45);
	for(;isdigit(c);c=getchar())x=(x<<1)+(x<<3)+(c^48);
	if(f)x=-x;return x;
}

#define fi first
#define se second
#define pb push_back
#define mkp make_pair
typedef pair<int,int>pii;
typedef vector<int>vi;

#define maxn 1500005
#define inf 0x3f3f3f3f

int n,m,a[maxn];
vi e[maxn];

int f[maxn][2],g[2];
void dfs(int u,int pa){
	int ch=0;
	f[u][0]=0,f[u][1]=-inf;
	for(int v:e[u]){
		if(v==pa)continue;
		dfs(v,u);
		++ch;
		For(i,0,1)For(j,0,1)g[i^j]=max(g[i^j],f[u][i]+f[v][j]);
		For(i,0,1)f[u][i]=g[i],g[i]=0;
	}
	f[u][!a[u]]+=1;
	if(!ch){
		f[u][a[u]]=0;
		f[u][!a[u]]=1;
	}
}

void work()
{
	n=read();
	For(i,1,n)a[i]=read();
	For(i,2,n){
		int u=read(),v=read();
		e[u].pb(v),e[v].pb(u);
	}
	dfs(1,0);
	cout<<max(f[1][0],f[1][1]);
}

signed main()
{
	int T=1;
	while(T--)work(); 
	return 0;
}