#include<fstream>
#include<list>
#include<bitset>
#include<climits>
using namespace std;
ifstream fin("asmax.in");
ofstream fout("asmax.out");
const int NMAX=16005,INF=INT_MAX;
list<int>g[NMAX];
bitset<NMAX>vis;
int cost[NMAX],n;
void read_data(){
    int from,to,i;
    fin>>n;
    for(i=1;i<=n;++i)
        fin>>cost[i];
    for(i=1;i<=n-1;++i){
        fin>>from>>to;
        g[from].push_back(to);
        g[to].push_back(from);
    }
}
void DFS(int node){
    bool isLeaf=true;
    list<int>::iterator it;
    vis[node]=true;
    for(it=g[node].begin();it!=g[node].end();++it)
        if(!vis[*it]){
            DFS(*it);
            cost[node]=max(cost[node],cost[*it]+cost[node]);
            isLeaf=false;
        }
    if(isLeaf)
        return ;
}
int get_maxDist(){
    int i,maxDist=-INT_MAX;
    for(i=1;i<=n;++i)
        maxDist=max(maxDist,cost[i]);
    return maxDist;
}
int main(){
    read_data();
    DFS(1);
    fout<<get_maxDist();
}