#include <fstream>
using namespace std;
ifstream in("asmax.in");
ofstream out("asmax.out");
const int N = 16002;
int val[N];
bool viz[N];
struct nod{
    int nr;
    nod *urm;
}*v[N];
void adaug(int x, int y){
    nod *p = new nod;
    p->nr = y;
    p->urm = v[x];
    v[x] = p;
}
void dfs(int ns){
    for(nod *p = v[ns];p;p = p->urm)
        if(viz[p->nr] == false){
            viz[p->nr] = true;
            dfs(p->nr);
            if(val[p->nr] > 0)
                val[ns] += val[p->nr];
        }
}
int main()
{
    int n,x,y;
    in>>n;
    for(int i=1;i<=n;i++)
        in>>val[i];
    for(int i=1;i<n;i++){
        in>>x>>y;
        adaug(x,y);
        adaug(y,x);
    }
    in.close();
    viz[1] = true;
    dfs(1);
    out<<val[1]<<"\n";
    out.close();
    return 0;
}