#include<cstdio>

#include<vector>

#include<cstring>

using namespace std;

const int maxn=;

int v[maxn];

int p[maxn];

vector<int> G[maxn];

int dp[maxn][];

void dfs(int u)

{

    dp[u][]=;

    dp[u][]=v[u];

    for (int i=;i<G[u].size();i++)

    {

        dfs(G[u][i]);

        dp[u][]+=max(dp[G[u][i]][],dp[G[u][i]][]);

        dp[u][]+=dp[G[u][i]][];

    }

}

int main()

{

    int n;

    while (scanf("%d",&n) && n)

    {

        memset(p,-,sizeof(p));

        for (int i=;i<=n;i++) G[i].clear();

        for (int i=;i<=n;i++) scanf("%d",&v[i]);

        for (int i=;i<=n-;i++)

        {

            int u,fa;

            scanf("%d%d",&u,&fa);

            p[u]=fa;

            G[fa].push_back(u);

        }

        int root;

        for (int i=;i<=n;i++) if (p[i]==-) root=i;

        dfs(root);

        printf("%d\n",max(dp[root][],dp[root][]));

    }

    return ;

}