#include <fstream>
#include <vector>

using namespace std;

const int LIM=16001;

ifstream cin("asmax.in");
ofstream cout("asmax.out");

int n, val[LIM], dp[LIM], sol=-(1<<30);
vector <int> arb[LIM];
char viz[LIM];
void dfs(int nod)
{
    viz[nod]=1;
    dp[nod]=val[nod];
    for(int i=0; i<arb[nod].size(); ++i)
        if(!viz[ arb[nod][i] ])
        {
            dfs(arb[nod][i]);
            if(dp[ arb[nod][i] ]>0) dp[nod]+=dp[ arb[nod][i] ];
        }
    if(dp[nod]<val[nod]) dp[nod]=val[nod];
    if(sol<dp[nod]) sol=dp[nod];
}
int main()
{
    cin>>n;
    for(int i=1; i<=n; ++i)
        cin>>val[i];
    for(int i=1; i<n; ++i)
    {
        int x, y;
        cin>>x>>y;
        arb[x].push_back(y);
        arb[y].push_back(x);
    }
    dfs(1);
    cout<<sol;
    return 0;
}