#include <fstream>
#include <vector>
using namespace std;
#define dmax 16001
vector <int > v[dmax];
int n, use[dmax], val[dmax];

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

void read()
{int a, b;
fin>>n;
for(int i=1;i<=n;i++)
    fin>>val[i];
for(int i=1;i<n;i++)
{
    fin>>a>>b;
    v[a].push_back(b);
    v[b].push_back(a);
}
}

int cut_tree(int vf)
{int k=0;
use[vf]=1;
    if(v[vf].size()==1)
    {
        if(val[vf]>0)
        return val[vf];
        else return 0;
    }
else
{
    for(int i=0;i<v[vf].size();i++)
    {
        if(use[v[vf][i]]==0)
if(cut_tree(v[vf][i])>0)
    k=k+cut_tree(v[vf][i]);
    }
if(k+val[vf]>0)
    return k+val[vf];
}

}

int main()
{

read();
fout<<cut_tree(1);
    return 0;
}