#include <fstream>
#include <vector>
#define DIM 16009

using namespace std;
ifstream f("asmax.in");
ofstream g("asmax.out");
vector < int > L[DIM];
int val[DIM], D[DIM], fr[DIM];
int n, i, x, y, sol;

void dfs ( int nod ){
    fr[nod] = 1;
    D[nod] = val[nod];
    for ( int i = 0; i < L[nod].size(); i++ ){
        int vecin = L[nod][i];
        if ( !fr[vecin] ){
            dfs ( vecin );
            if ( D[vecin] > 0 )
                D[nod] += D[vecin];
        }
    }
    sol = max ( sol, D[nod] );
}

int main()
{
    f>>n;
    for ( i=1; i <= n; i++ )
        f>>val[i];
    for ( i=1; i < n; i++ ){
        f>>x>>y;
        L[x].push_back(y);
        L[y].push_back(x);
    }
    dfs ( 1 );
    g<<sol;
    return 0;
}