#include<bits/stdc++.h>
#define maxn 2600 
using namespace std;
int n,a[maxn],a1,a2,su1,su2,d[maxn],ans;
vector<int>b[maxn];
void solve(int p,int fa,int sd){
	d[p]=sd;
	for(int i=0;i<b[p].size();i++){
		int x=b[p][i];
		if(x==fa)continue;
		solve(x,p,sd+1);
	}
	return;
}
int main(){
	freopen("usaco_Feb_clocktree.in","r",stdin);
	freopen("usaco_Feb_clocktree.out","w",stdout);
	scanf("%d",&n);
	for(int i=1;i<=n;i++)scanf("%d",&a[i]);
	for(int i=1;i<=n-1;i++)scanf("%d%d",&a1,&a2),b[a1].push_back(a2),b[a2].push_back(a1);
	solve(1,0,0);a1=a2=0;
	for(int i=1;i<=n;i++){
		if(d[i]%2)su1+=a[i],a1++;
		else su2+=a[i],a2++;
	}
	if(su1%12==su2%12)ans=n;
	if((su1+1)%12==su2%12)ans=a2;
	if((su1+11)%12==su2%12)ans=a1;
	printf("%d\n",ans);
	return 0;
}