#include<cstdio>
#include<vector>
using namespace std;
int n;
int viz[16010],v[16010];
vector<int> a[16010];
void read()
{
    int i,x,y;
    freopen("asmax.in","r",stdin);
    freopen("asmax.out","w",stdout);
    scanf("%d",&n);
    for(i=1;i<=n;i++)
        scanf("%d",&v[i]);
    for(i=1;i<n;i++)
        {
            scanf("%d%d",&x,&y);
            a[x].push_back(y);
            a[y].push_back(x);
        }
}

void dfs(int x)
{
    viz[x]=1;
    for(vector<int> :: iterator i=a[x].begin();i!=a[x].end();i++)
    {
        if(!viz[*i])
        {
            dfs(*i);
            if(v[*i]>0)
                v[x]+=v[*i];
        }
    }
}

void rez()
{
    int i,max=-16000010;
    dfs(1);
    for(i=1;i<=n;i++)
        if(v[i]>max)
            max=v[i];
    printf("%d\n",max);
}

int main()
{
    read();
    rez();
    return 0;
}