#include <iostream>
#include <fstream>
#include <vector>
#define NMAX 16050

using namespace std;

int n,val[NMAX], tata[NMAX];
int din[NMAX]; /// din[i]=suma maxima a unui subarbore cu radacina in nodul i
int sm=-999999999;
vector <int> graf[NMAX];

void dfs(int nod)
{
    din[nod]=val[nod];
    sm=max(sm,val[nod]);
    for(int i=0; i<graf[nod].size();i++)
    {
        int vecin=graf[nod][i];
        if(tata[nod]!=vecin)
        {
            tata[vecin]=nod;
            dfs(vecin);
            if(din[vecin]>0)
                din[nod]+=din[vecin],sm=max(sm,din[nod]);
        }
    }
}

int main()
{
    ifstream fin("asmax.in");
    ofstream fout("asmax.out");
    fin>>n;
    for(int i=1;i<=n;i++)
        fin>>val[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);
    }
    dfs(1);
    fout<<sm;
    return 0;
}