#include<cstdio>
#include<vector>
using namespace std;
#define NMAX 16005
vector <int> a[NMAX];
int n,x,y,Max,cost[NMAX],v[NMAX],S[NMAX];

void dfs(int s)
{
    int i;
    v[s] = 1;
    S[s] = cost[s];
    for (i=0;i<a[s].size();++i)
        if (!v[a[s][i]]){
            dfs(a[s][i]);
            if (S[a[s][i]]>0)
                S[s] += S[a[s][i]];
        }
    if (Max<S[s])
        Max=S[s];
}
int main()
{
    int i;
    freopen("asmax.in","r",stdin);
    freopen("asmax.out","w",stdout);
    scanf("%d",&n);
    for (i=1;i<=n;++i)
        scanf("%d",&cost[i]);
    for (i=1;i<n;++i)
        {
            scanf("%d%d",&x,&y);
            a[x].push_back(y);
            a[y].push_back(x);
        }
    dfs(1);
    printf("%d\n",Max);
    return 0;
}