#include <cstdio>
#include <vector>

using namespace std;

struct node{
	int seen;
	int val,max;
	vector<int> children;
};

node* mat[16001];

void dfs(int x){
	mat[x]->seen=1;
	int t,j;
	for(j=0;j<mat[x]->children.size();j++){
		t=mat[x]->children[j];
		if(mat[t]->seen==0){
			dfs(t);
			if(mat[t]->max>0)
				mat[x]->max+=mat[t]->max;
		}
	}
}

int main(){
	freopen("asmax.in","rt",stdin);
	freopen("asmax.out","wt",stdout);
	
	int n,i,j;
	scanf("%d",&n);
	for(i=1;i<=n;i++){
		mat[i]=new node;
		scanf("%d",&(mat[i]->val));
		mat[i]->max=mat[i]->val;
	}
	int a,b;
	for(i=1;i<n;i++){
		scanf("%d%d",&a,&b);
		mat[a]->children.push_back(b);
		mat[b]->children.push_back(a);
	}
	
	dfs(1);
	int max=mat[1]->max;
	for(i=2;i<=n;i++)
		if(mat[i]->max>max)
			max=mat[i]->max;
	printf("%d",max);
	
	return 0;
}