#include<stdio.h>
#include<vector>
using namespace std;
vector<int> nr[16100];
int N,SOL;
int val[16100],s[16100];
char viz[16100];
void df(int x){
	viz[x]=1;
	for(vector<int>::iterator it=nr[x].begin();it!=nr[x].end();++it){
		if(!viz[*it])
			df(*it);
	}
	int su=0,mx=-10000;
	for(vector<int>::iterator it=nr[x].begin();it!=nr[x].end();++it){
		if(viz[*it]!=2)
			continue;
		if(s[*it]>0)
			su+=s[*it];
		if(s[*it]>mx)
			mx=s[*it];
	}
	if(mx>su+val[x])
		s[x]=mx;
	else
		s[x]=val[x]+su;
	if(SOL<s[x])
		SOL=s[x];
	viz[x]=2;
}
int main(){
	freopen("asmax.in","r",stdin);
	freopen("asmax.out","w",stdout);
	int x,y,i,neg=-100000;
	scanf("%d",&N);
	for(i=1;i<=N;++i){
		scanf("%d",&val[i]);
		if(val[i]>neg)
			neg=val[i];
	}
	if(neg<=0){
		printf("%d\n",neg);
		return 0;
	}
	for(i=1;i<N;++i){
		scanf("%d%d",&x,&y);
		nr[x].push_back(y);
		nr[y].push_back(x);
	}
	SOL=-1000000;
	df(1);
	printf("%d\n",SOL);
	fclose(stdin);
	fclose(stdout);
	return 0;
}