#include<iostream>
#include<stdio.h>
#include<string.h>
using namespace std;

const int N = 16010;
int e[N],ne[N],h[N];
int f[N],a[N];
bool have_father[N];
int n,idx;

void add(int a,int b)
{
  e[++idx] = b;
  ne[idx] = h[a];
  h[a] = idx;
}

void dp(int x)
{
  if(f[x] == 0x3f3f3f3f) f[x] = a[x]; 
  
  for(int i = h[x];i != -1;i = ne[i])
  {
    int j = e[i];
    
    dp(j);
	if(f[j] <= 0) continue;
	else f[x]+= f[j];  
  }
}

int main()
{
  scanf("%d",&n);
  memset(h,-1,sizeof(h));
  memset(f,0x3f,sizeof(f));
  
  for(int i = 1;i <= n;i++) scanf("%d",&a[i]);
  for(int i = 1;i < n;i++)
  {
    int a,b;
    scanf("%d%d",&a,&b);
    
    add(b,a);
    have_father[a] = true;
  }
  
  int root;
  for(int i = 1;i <= n;i++)
   if(!have_father[i])
   {
	 root = i;
	 break;
   }

  dp(root);
  printf("%d",f[root]);
  
  return 0;
}