#include <algorithm>
#include <fstream>
#include <vector>
#include <stack>

using namespace std;

ifstream f("asmax.in");
ofstream g("asmax.out");

const int mare = 16000, fmare = 16000000;
vector <int> ls[16005];
int n, i, x, y;
int a[16005], nmin = mare;
int sf[16005] = {-fmare}, smax = -fmare;
bool viz[16005];

int df(int k){
    int i, l = ls[k].size();
    viz[k] = 1;
    sf[k] = a[k];
    for (i = 0; i < l; i++){
        if (viz[ls[k][i]] == 0){
            x = df(ls[k][i]);
            if (x > 0)
                sf[k] += x;
        }
    }
    return sf[k];
}

int main(){
    f >> n;
    for (i = 1; i <= n; i++)
        f >> a[i];

    for (i = 1; i <= n-1; i++){
        f >> x >> y;
        ls[x].push_back(y);
        ls[y].push_back(x);
    }
    df(1);
    for (i = 1; i <= n; i++)
        if (smax < sf[i])
            smax = sf[i];
    g << smax;
    return 0;
}