#include<stdio.h>
#include<vector>
using namespace std;

int v[16001],s[16001];
char f[16001];
vector <int> c[16001];

void dfs(int nod)
{
    f[nod]=1;
    s[nod]=v[nod];
    vector <int>::iterator it;
    for(it=c[nod].begin();it!=c[nod].end();it++)
    {
        if(f[*it]==0)
        {
            dfs(*it);
            if(s[*it]>0)
                s[nod]+=v[*it];
        }
    }
}

int main()
{
    freopen("asmax.in","r",stdin);
    freopen("asmax.out","w",stdout);
    int n,i,x,y,sol=-2000000000;
    scanf("%d",&n);
    for(i=1;i<=n;i++)
        scanf("%d",&v[i]);
    for(i=1;i<n;i++)
    {
        scanf("%d%d",&x,&y);
        c[x].push_back(y);
        c[y].push_back(x);
    }
    dfs(1);
    for(i=1;i<=n;i++)
        if(s[i]>sol)
            sol=s[i];
    printf("%d\n",sol);
    return 0;
}