#include <fstream>
#include <vector>
using namespace std;
ifstream in("asmax.in");
ofstream out("asmax.out");

bool viz[200001];
vector <int> arb[200001];
int n, val[200001], maxim=-100000;

void dfs(int x)
{
    int i;
    viz[x]=true;
    for(i=0;i<arb[x].size();i++)
        if(!viz[arb[x][i]])
        {
            dfs(arb[x][i]);
            if(val[arb[x][i]]>0)
            {
                val[x]=val[x]+val[arb[x][i]];
                if(val[x]>maxim)
                    maxim=val[x];
            }
        }
}

int main()
{
    int i, x, y;
    in>>n;
    for(i=1;i<=n;i++)
    {
        in>>val[i];
        if(val[i]>maxim) maxim=val[i];
    }
    for(i=1;i<n;i++)
    {
        in>>x>>y;
        arb[x].push_back(y);
        arb[y].push_back(x);
    }
    dfs(1);
    out<<maxim;
    return 0;
}