#include <bits/stdc++.h>
#define N 16010
using namespace std;

int sum,bestsum = -(2e9),n,a,b;
int val[N];
vector <int> v[N];

void dfs(int x)
{
    if(sum<0) sum = val[x];
    else sum+=val[x];
    if(bestsum<sum) bestsum = sum;
    for(int i=0;i<v[x].size();i++)
    {
        dfs(v[x][i]);
    }

}

int main()
{
    ifstream cin("asmax.in");
    ofstream cout("asmax.out");
    cin>>n;
    for(int i=1;i<=n;i++)
        cin>>val[i];
    for(int i=1;i<n;i++)
    {
        cin>>a>>b;
        v[a].push_back(b);
    }
    dfs(1);
    cout<<bestsum;

    return 0;
}