#include <stdio.h>
FILE *f;
int n,i,v[16001],k,s[16001],tmax,sum[16001],max,p[16001],t,a,b,q[16001],used[6001];
struct asdf {
	int x,y;
} r[32005];
static int cmp (const void * a,const void *b)
{
	struct asdf * aa = (struct asdf*) a;
	struct asdf * bb = (struct asdf*) b;
	if (aa->x == bb->x)
	return aa->y - bb->y;
	else
	return aa->x - bb->x;
}
int main (void)
{
	f=fopen("asmax.in","r");
	fscanf(f,"%d",&n);
	for(i=1;i<=n;i++)
	fscanf(f,"%d",&v[i]);
	for(i=1;i<n;i++)	
	{
	fscanf(f,"%d %d",&r[i].x,&r[i].y);
	r[i+n].x=r[i].y;
	r[i+n].y=r[i].x;
	}
	qsort(r+1,n*2-2,sizeof(r[0]),cmp);
	k=1;
	for(i=1;i<=2*n;i++)
		if (r[i].x==k) {s[k]=i;k++;}
	a=1;
	b=2;
	q[1]=1;
	used[1]=1;
	s[2*n+1]=k;
	do
	{
		t=q[a];
		for(i=s[t];i<s[t+1];i++)
			if (!used[r[i].y]) {q[b++]=r[i].y;used[r[i].y]=1;p[r[i].y]=t;}
		a++;
	} while (a<b);
	max=0;
	for(i=n;i>=1;i--)
	{
		t=q[i];
		tmax=sum[t]+v[t];
		if (tmax > max) max=tmax;
		if (tmax>0) sum[p[t]]+=tmax;
		printf("t=%d tmax=%d sum[t]=%d v[t]=%d\n",t,tmax,sum[t],v[t]);
	}
	f=fopen("asmax.out","w");
	fprintf(f,"%d\n",max);
	fclose(f);
}