#include <cstdio>
#include <vector>
using namespace std;
int N,i,x,y,l,val[16005],tata[16005],maxim=-(1<<30);
vector <int> graf[16005];
void DFS(int nod)
{
    vector <int>::iterator it;
    for (it=graf[nod].begin();it!=graf[nod].end();it++)
    {
        if (*it==tata[nod]) continue;
        tata[*it]=nod;
        DFS(*it);
        if (val[*it]>0) val[nod]+=val[*it];
        if (val[nod]>maxim) maxim=val[nod];
    }
}
int main()
{
    freopen("asmax.in","r",stdin);
    freopen("asmax.out","w",stdout);
    scanf("%d",&N);
    for (i=1;i<=N;i++) scanf("%d",&val[i]);
    for (i=1;i<N;i++)
    {
        scanf("%d %d",&x,&y);
        graf[x].push_back(y);
        graf[y].push_back(x);
    }
    DFS(1);
    printf("%d",maxim);
    return 0;
}