#include <iostream>
#include <fstream>
#include <vector>
using namespace std;
ifstream f("asmax.in");
ofstream g("asmax.out");
const int N=50001;
vector<int> a[N];
int n,c[N],p[N];
bool viz[N];
void citire()
{
    int x,y;
    f>>n;
    for(int i=1; i<=n; ++i)
        f>>c[i];
    for(int i=1; i<=n-1; ++i)
    {
        f>>x>>y;
        a[x].push_back(y);
        a[y].push_back(x);
    }
}
void dfs(int x)
{
    int y;
    viz[x] = true;
    p[x]=c[x];
    for(size_t i=0; i<a[x].size(); ++i)
    {
        y=a[x][i];
        if (!viz[y])
        {
            dfs(y);
            if(p[y]>0)
                p[x]+=p[y];
        }
    }
}
int main()
{
    citire();
    int max=-1001;
    dfs(1);
    for(int i=1; i<=n; ++i)
        if (p[i]>max) max = p[i];
    g<<max;
    return 0;
}