#include<cstdio>
#include<vector>
using namespace std;
vector<int>v[16010];
int n,viz[16010],val[16010],c[16010],smax;
void citire()
{
    int x,y;
    scanf("%d",&n);
    for(int i=1;i<=n;i++)
    {
        scanf("%d",&c[i]);
        val[i]=c[i];
    }
    for(int i=1;i<n;i++)
    {
        scanf("%d%d",&x,&y);
        v[x].push_back(y);
        v[y].push_back(x);
    }
}
void dfs(int x)
{
    viz[x]=1;
    for(int i=0;i<v[x].size();i++)
    {
        int y=v[x][i];
        if(viz[y]==0)
        {
            dfs(y);
            if(val[x]<val[x]+val[y])
                val[x]=val[x]+val[y];
            if(val[x]<val[y]+c[x])
                val[x]=val[y]+c[x];
            if(val[x]<c[x])
                val[x]=c[x];
            if(val[x]>smax)
                smax=val[x];
        }
    }
    if(val[x]>smax)
                smax=val[x];
}
int main()
{
    freopen("asmax.in","r",stdin);
    freopen("asmax.out","w",stdout);

    citire();
    smax=-1999999999;
    dfs(1);
    printf("%d",smax);
    return 0;
}