#include <iostream>
#include <fstream>
#include <vector>
using namespace std;
ifstream fin("asmax.in");
ofstream fout("asmax.out");
vector<vector<int>>graf;
bool viz[20005];
int a[20005];
int dfs(int nod){
    viz[nod]=true;
    int maxim = -1e9;
    for(int vec:graf[nod]){
        if(a[vec]>0){
            a[nod]=a[nod]+a[vec];
        }

        /*if(!viz[vec]){
            maxim = max(maxim, dfs(vec));
        }*/
    }
    if(a[nod]>maxim){
        maxim=a[nod];
    }
    return maxim;
}
int main()
{
    int n;
    fin>>n;
    graf.resize(n+1);
    for(int i=1;i<=n;i++){
        fin>>a[i];
    }
    for(int i=1;i<=n-1;i++){
        int x,y;
        fin>>x>>y;
        graf[x].push_back(y);
        graf[y].push_back(x);
    }
    fout<<dfs(1);

    return 0;
}