#include<stdio.h>

#include<vector>

using namespace std;

vector <int> v[16005];
int n,k,viz[16005],nr,a,b,x[16005];
int recur ( int poz)
{
	int i,q,sum,knr;
    q=v[poz].size();
	for(i=0;i<q;i++)
		if(viz[v[poz][i]]==0)
        {
			knr=recur(v[poz][i]);
            if(knr>0)
                sum=sum+knr;
        }
    sum=sum+x[poz];
    return sum;
}
int main ()
{		
		int i;
		freopen( "asmax.in" , "r" , stdin);
		freopen( "asmax3.out" , "w" , stdout);
		scanf("%d",&n);
        for(i=1;i<=n;i++)
            scanf("%d",&x[i]);
		for(i=1;i<=n-1;i++)
		{
			scanf("%d%d",&a,&b);
            v[a].push_back(b);

		}
        nr=recur(1);
        printf("%d",nr);
		return 0;
}