#include <iostream>
#include <fstream>
#include <vector>
using namespace std;

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

const int N=16001;
vector<int> a[N];
int n,v[N],d[N];
bool viz[N];
void citire()
{
    int x,y,i;
    in>>n;
    for(i=1; i<=n; i++)
        in>>v[i];
    for(i=1; i<n; i++)
    {
        in>>x>>y;
        a[x].push_back(y);
        a[y].push_back(x);
    }
    in.close();
}

int dfs(int nod)
{
    int y,rez,val,i;
    viz[nod]=1;
    rez=v[nod];
    for(i=0; i<a[nod].size(); i++)
    {
        y=a[nod][i];
        if(viz[y]==0)
        {
            val=dfs(y);
            if(val>0)
                rez=rez+val;
        }
    }
    return rez;
}
int main()
{
    citire();
    out<<dfs(1);
    return 0;
}