#include<cstdio>
#include<vector>
using namespace std;
vector <int> v[16001];
int sum[16001],viz[16001],val[16001],smax;
void dfs(int nod)
{
    int i;
    sum[nod]=val[nod];
    viz[nod]=1;
    for(i=0;i<v[nod].size();i++)
        if(viz[v[nod][i]]==0)
        {
            dfs(v[nod][i]);
            if(sum[v[nod][i]]>0)
            {
                sum[nod]=sum[nod]+sum[v[nod][i]];
                if(smax<sum[nod])
                    smax=sum[nod];
            }
        }
}
int main()
{
    freopen("asmax.in","r",stdin);
    freopen("asmax.out","w",stdout);
    int n,i,x,y;
    scanf("%d",&n);
    for(i=1;i<=n;i++)
    {
        scanf("%d",&val[i]);
    }
    for(i=1;i<=n-1;i++)
    {
        scanf("%d%d",&x,&y);
        v[x].push_back(y);
        v[y].push_back(x);
    }
    for(i=1;i<=n;i++)
    {
        if(viz[i]==0)
            dfs(i);
    }
    printf("%d",smax);
    return 0;
}