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

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

const int N=16001;
const int M=2*N;

int v[N], urm[2*M], lst[N], vf[2*M], nr;
bool viz[N];
void adauga(int x, int y)
{
    vf[++nr]=y;
    urm[nr]=lst[x];
    lst[x]=nr;
}

void dfs(int x)
{
    viz[x]=true;
    for(int p=lst[x];p!=0;p=urm[p])
    {
        int y=vf[p];
        if(!viz[y])
        {
            dfs(y);
            if(v[y]>0)
               v[x]=v[x]+v[y];
        }
    }
}

int main()
{
    int n;
    fin>>n;
    for(int i=1;i<=n;i++)
        fin>>v[i];
    for(int i=1;i<=n-1;i++)
    {
        int x,y;
        fin>>x>>y;
        adauga(x,y);
        adauga(y,x);
    }
    dfs(1);
    int maxx=-1e9;
    for(int i=1;i<=n;i++)
        if(v[i]>=maxx)
        maxx=v[i];
    fout<<maxx;
    return 0;
}