#include <fstream>
#include<vector>
using namespace std;
const int N=16000;
int v[N+1],viz[N+1];
vector<int>a[N+1];
int n;

ifstream f("asmax.in");
ofstream g("asmax.out");

void dfs(int nod){
    viz[nod]=1;
    for(int i=0;i<a[nod].size();i++)
        if(viz[a[nod][i]]==0){
            dfs(a[nod][i]);
            if(v[a[nod][i]]>0)
                v[nod]=v[nod]+v[a[nod][i]];
        }
}
int main()
{
    f>>n;
    int i,x,y,max;
    for(i=1;i<=n;i++)
        f>>v[i];
    for(i=1;i<n;i++){
        f>>x>>y;
        a[x].push_back(y);
        a[y].push_back(x);
    }
    for(i=1;i<=n;i++)
    dfs(1);
    max=v[1];
    for(i=2;i<=n;i++)
        //g<<v[i]<<" ";
        if(max>v[1])
            max=v[1];
    g<<max<<"\n";
    return 0;
}