#include <iostream>
#include <fstream>
#include <vector>
using namespace std;
ifstream in ("asmax.in");
ofstream out("asmax.out");
int const N=16005;
vector <int> a[N];
int n,maxim,aux,val[N];
bool calculat[N];
void citire()
{
    int x,y;    in>>n;
    for(int i=1;i<=n;i++)
        in>>val[i];
    for(int i=1;i<=n;i++)
    {
        in>>x>>y;
        a[x].push_back(y);
        //a[y].push_back(x);
    }
}
int dfs(int x)
{
    if(calculat[x]) return val[x];
    for(size_t i=0;i<a[x].size();i++)
    {
        aux=dfs(a[x][i]);
        if(aux>0)   val[x]+=aux;
    }
    calculat[x]=true;
    return val[x];
}
int main()
{
    citire();
    for(int i=1;i<=n;i++)
    {
        aux=dfs(i);
        if(aux>maxim)
            maxim=aux;
    }
    out<<maxim<<"\n";
    return 0;
}