#include<cstdio>
#include<vector>
#include<algorithm>
#define NMAX 16000+5
using namespace std;
bool b[NMAX];
int v[NMAX],s[NMAX],i,x,y,n,smax,prev[NMAX];
vector<int> a[NMAX];
void getsum(int x)
{
    int y;
    if(b[x]) return;
    b[x]=1; s[x]=v[x];
    if(a[x].size()==0) return;
    int p=a[x].size();
    for(int i=0;i<p;i++)
    {
        y=a[x][i];
        if(b[y]==0) getsum(y);
        if(s[y]>=0) s[x]=s[x]+s[y];
    }
}
int main()
{
    freopen("asmax.in","r",stdin);
    freopen("asmax.out","w",stdout);
    scanf("%d",&n);
    for(i=1;i<=n;i++) scanf("%d",&v[i]);
    for(i=1;i<=n-1;i++)
    {
        scanf("%d%d",&x,&y);
        if(prev[y]) swap(x,y);
        a[x].push_back(y);
        prev[y]=x;
    }
    smax=-(1<<30);
    for(i=1;i<=n;i++)
    {
        getsum(i);
        smax=max(s[i],smax);
    }
    printf("%d\n",smax);
    return 0;
}