#include <stdio.h>
#include <vector>

using namespace std;

#define FIN "asmax.in"
#define FOUT "asmax.out"
#define nmax 1<<14

#define FOR(i,a,b) for(i= (a); i<(b); ++i)

vector<int> a[nmax];
int c[nmax], v[nmax], MAX=-(1<<20), NEG;
int s[nmax], n;

void DF(int nod)
 {
  int i;

  v[nod]=1;

  FOR(i,0,a[nod].size())
   if(v[a[nod][i]]==0)
    {
     DF(a[nod][i]);
     if( s[a[nod][i]] > 0 )
      s[nod] += s[a[nod][i]];
    }

  s[nod]+= c[nod];
  
  if(s[nod] > 0) 
   NEG=1;
   
  if( s[nod] > MAX)
   MAX = s[nod]; 
 }
int main()
 {
   freopen(FIN,"r",stdin);
   freopen(FOUT,"w",stdout);

   int i,x,y;
   
   scanf("%i\n", &n);

   FOR(i,1,n) 
    scanf("%i", &c[i]);


   FOR(i,1,n)   
   {
     scanf("%i%i", &x,&y);
     a[x].push_back(y);
     a[y].push_back(x);
   }

   DF(1);

   if(NEG)
    printf("%i\n", MAX);
     else
    {
     ++n;
     MAX=c[1];
     FOR(i,2,n);
      if(c[i] > MAX)
       MAX = c[i];
     printf("%i\n", MAX);
    }
 
   return 0;
 }