#include<fstream>
#include<vector>
using namespace std;

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

int n;
vector<int> a;

int p[16001];
int q[16001];

bool s[16001];

vector<vector<int> > G;

void Read();
void Solve();
void DF(int x);

int main()
{
    Read();
    Solve();
    
    fin.close();
    fout.close();
    
    return 0;
}

void Read()
{
     fin >> n;
     a.resize(n+1);
     G.resize(n+1);
     
     for( int i = 1; i <= n; ++i )
          fin >> a[i];
     
     int x, y;
     
     for( int i = 1; i <= n-1; ++i )
     {
          fin >> x >> y;
          G[x].push_back(y);
          G[y].push_back(x);
     }
}

void Solve()
{
     DF(1);
     fout << max( p[1], q[1] );
}

void DF( int x )
{
     s[x] = true;
     
     if( G[x].size() == 1 )
     {
         p[x] = a[x];
         q[x] = 0;
         return;
     }
     
     for( int i = 0; i < G[x].size(); ++i )
          if( !s[ G[x][i] ] )
          {
              DF( G[x][i] );
              p[x] = max( p[x]+p[ G[x][i] ], p[x] + q[ G[x][i] ]);
              q[x] = max( q[x] + p[ G[x][i] ], q[x] + q[ G[x][i] ] );
          }
}