#include<iostream>

#include<cstring>

#include<cmath>

#include<queue>

#include<algorithm>

#include<cstdio>

#define max(a,b) a>b?a:b

using namespace std;

#define LL long long

#define INF 0x3f3f3f3f

const int N=;

struct Eage

{

    int from,to;

    int next;

}eage[N<<];

int val[N],out[N];

int dp[N][];   //dp[i][0]表示i不去，dp[i][1]表示i去

int ans,head[N];    //head记录边的次序

void add_eage(int a,int b)  //难点，理解边，构树

{

    eage[ans].from=a;

    eage[ans].to=b;

    eage[ans].next=head[b];

    head[b]=ans++;

}

void dfs(int root)

{

    dp[root][]=;

    dp[root][]=val[root];

    for(int i=head[root];i!=-;i=eage[i].next){     //dfs所有指向root点的边

        int s=eage[i].from;

        dfs(s);

        //状态转移。root去，他的下属就不能去；root不去，就取他下属去或不去的最大值

        dp[root][]+=max(dp[s][],dp[s][]);

        dp[root][]+=dp[s][];

    }

}

int main()

{

    int n;

    while(scanf("%d",&n)!=EOF)

    {

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

            scanf("%d",&val[i]);

        }

        memset(out,,sizeof(out));

        memset(head,-,sizeof(head));

        int a,b;

        ans=;

        while(scanf("%d%d",&a,&b),a||b){

            out[a]++;

            add_eage(a,b);

        }

        int root;

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

            if(!out[i]){    //出度为0即根结点

                root=i;

                break;

            }

        }

        memset(dp,,sizeof(dp));

        dfs(root);

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

    }

    return ;

}