#include<cstdio>
#include<vector>
using namespace std;
vector <int> l[16001];
int viz[16001],v[16001];



int dfs(int u)
{
    int s=0,t;
    vector<int>::iterator it;
    viz[u]=1;
    s+=v[u];
    for(it=l[u].begin();it!=l[u].end();++it)
        if(!viz[*it])
        {
            t=dfs(*it);
            if(t>0)
                s+=t;
        }
    return s;
}





int main()
{
    freopen("asmax.in","r",stdin);
    freopen("asmax.out","w",stdout);
    int n,i;
    scanf("%d",&n);
    for(i=1;i<=n;++i)
        scanf("%d",&v[i]);
    int u,v;
    for(i=1;i<n;++i)
    {
        scanf("%d%d",&u,&v);
        l[u].push_back(v);
        l[v].push_back(u);
    }
    printf("%d\n",dfs(1));
    return 0;
}