#include<stdio.h>
#include<vector>
using namespace std;
#define nmax 16005
long n, i, a, b, rez;
long v[nmax], s[nmax];
vector <long> ma[nmax];
bool viz[nmax];

void citire()
{
    scanf("%ld",&n);
    for (i=1;i<=n;i++)
        scanf("%ld",&v[i]);
    for (i=1;i<=n-1;i++)
    {
        scanf("%ld %ld",&a,&b);
        ma[a].push_back(b); ma[b].push_back(a);
    }
}

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

int main()
{
    freopen("asmax.in","r",stdin);
    freopen("asmax.out","w",stdout);
    rez=-nmax*1000;
    citire();
    dfs(1);
    printf("%ld",rez);
    return 0;
}