#include<fstream>
#include<vector>
using namespace std;
ifstream f("asmax.in");
ofstream g("asmax.out");
int n, smax=-100000000, z[16001];
bool viz[16001];
vector <int> v[16001];
void citire()
{
    int i, j, x, y;
    f>>n;
    for(i=1;i<=n;i++)f>>z[i];
    for(i=1;i<=n-1;i++)
    {
        f>>x>>y;
        v[x].push_back(y);
        v[y].push_back(x);
    }
}
void dfs(int x)
{
    int i;
    viz[x]=1;
    for(i=0;i<v[x].size();i++)
    {
        if(!viz[v[x][i]])
        {
            dfs(v[x][i]);
            if(z[v[x][i]]>0)z[x]+=z[v[x][i]];
        }
    }
}
int main()
{
    citire();
    int i;
    dfs(1);
    for(i=1;i<=n;i++)if(z[i]>smax)smax=z[i];
    g<<smax;
    f.close();
    g.close();
    return 0;
}