#include<stdio.h>
#define dim 16005
using namespace std;

int i,n,p,x,j,y,rad,cost[dim],mat[dim][dim],viz[dim],nod[dim],s[dim];
long long max=-99999999;

void bfs()
{
i=1; j=1; viz[1]=1; s[1]=cost[1]; nod[i]=1;

while(i<=j)
{x=nod[i];
 for(p=1; p<=mat[x][0]; p++)
	if(!viz[mat[x][p]])
	{y=mat[x][p];
	 viz[y]=1;
	 j++; nod[j]=y;
	 if(s[x]+cost[y]>0) {s[x]=s[x]+cost[y]; s[y]=s[x];}
	 else s[y]=cost[y];
	 
	 if(s[y]>max) max=s[y];
	}
i++;
}

 
}
   



int main()
{
 FILE *f=fopen("asmax.in","r"), *g=fopen("asmax.out","w");
 
 fscanf(f,"%d",&n);
  for(i=1; i<=n; i++)
 fscanf(f,"%d",&cost[i]); 

  
  for(i=1; i<n; i++)
 {fscanf(f,"%d%d",&x,&y);
  mat[x][0]++; mat[x][mat[x][0]]=y;
  mat[y][0]++; mat[y][mat[y][0]]=x;
 }
 
 bfs(); 
  
 fprintf(g,"%lld\n",max);
 
fclose(f);
fclose(g);
return 0;
}