#include <fstream>
#include <vector>

using namespace std;

const int NMAX= 16000, inf= (1<<30);

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

vector <int> g[NMAX+1];
int d[NMAX+1], v[NMAX+1];
int viz[NMAX+1];

void dfs( int nod )
{
    viz[nod]= 1;
    d[nod]= v[nod];

    for( int i= 0; i<(int)g[nod].size(); ++i )
    {
        if( viz[ g[nod][i] ]==0 )
        {
            dfs( g[nod][i] );

            if( d[ g[nod][i] ]>0 )
            {
                d[nod]+= d[ g[nod][i] ];
            }
        }
    }
}

int main(  )
{
    int N, ans= -inf;
    in >> N;

    for( int i= 1; i<=N; ++i )
    {
        in >> v[i];
    }

    for( int i= 1; i<N; ++i )
    {
        int x, y;
        in >> x >> y;
        g[x].push_back(y);
        g[y].push_back(x);
    }
    dfs(1);
    for( int i= 1; i<=N; ++i )
    {
        if ( d[i]>ans )
        {
            ans= d[i];
        }
    }

    out << ans << '\n';

    return 0;
}