There is going to be a party to celebrate the 80-th Anniversary of the Ural State University. The University has a hierarchical structure of employees. It means that the supervisor relation forms a tree rooted at the rector V. E. Tretyakov. In order to make the party funny for every one, the rector does not want both an employee and his or her immediate supervisor to be present. The personnel office has evaluated conviviality of each employee, so everyone has some number (rating) attached to him or her. Your task is to make a list of guests with the maximal possible sum of guests' conviviality ratings. 

7

1

1

1

1

1

1

1

1 3

2 3

6 4

7 4

4 5

3 5

0 0

5

#include<cstdio>

#include<cstdlib>

#include<cstring>

#include<iostream>

#include<algorithm>

#include<memory>

using namespace std;

const int maxn=;

int vis[maxn],V[maxn],ans,cnt,dp[maxn][];

int Laxt[maxn],Next[maxn],To[maxn],ru[maxn];

void add(int u,int v){

    Next[++cnt]=Laxt[u];

    Laxt[u]=cnt;

    To[cnt]=v;

}

int dfs(int u)

{

    vis[u]=;

    dp[u][]=V[u];

    for(int i=Laxt[u];i;i=Next[i]){

         int v=To[i];

         if(!vis[v]){

            dfs(v);

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

            dp[u][]+=max(dp[v][],dp[v][]);

         }

    }

}

int main()

{

    int i,j,k,n,u,v;

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

        cnt=;ans=;

        memset(Laxt,,sizeof(Laxt));

        memset(dp,,sizeof(dp));

        memset(ru,,sizeof(ru));

        memset(vis,,sizeof(vis));

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

        for(;;){

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

           if(u==&&v==) break;

           add(v,u);

           ru[u]++;

        }

        for(i=;i<=n;i++) {

          if(ru[i]==) {

              dfs(i);

              ans+=max(dp[i][],dp[i][]);//防止多棵树

          }

         }

        printf("%d\n",ans);

    }

    return ;

}