#include<bits/stdc++.h>
#define maxN 16005
using namespace std;
int sum[maxN],val[maxN],sol,n,a,b,seen[maxN];
vector<int> v[maxN];
void dfs(int nod)
{
    seen[nod]=1;
    sum[nod]=val[nod];
    for(vector<int>::iterator it=v[nod].begin();it!=v[nod].end();it++)
    {
        if(!seen[*it])
        {
        dfs(*it);
        if(sum[*it]>0) sum[nod]+=sum[*it];
        }
    }
    sol=max(sol,sum[nod]);
}
int main()
{
    freopen("asmax.in","r",stdin);
    freopen("asmax.out","w",stdout);
    scanf("%d",&n);
    for(int i=1;i<=n;i++) scanf("%d",&val[i]);
    for(int i=1;i<n;i++)
    {
        scanf("%d%d",&a,&b);
        v[a].push_back(b);
        v[b].push_back(a);
    }
    sol=-INT_MAX;
    dfs(1);
    printf("%d\n",sol);
    return 0;
}