#include<iostream>

#include<cstdio>

#include<cstring>

#include<algorithm>

#include<queue>

#include<vector>

using namespace std;

inline int read(){

    int sum=,x=;

    char ch=getchar();

    while(ch<''||ch>''){

        if(ch=='-')

            x=;

        ch=getchar();

    }

    while(ch>=''&&ch<=''){

        sum=(sum<<)+(sum<<)+(ch^),ch=getchar();

    }

    return x?sum:-sum;

}

inline void write(int x){

    if(x<)

        putchar('-'),x=-x;

    if(x>)

        write(x/);

    putchar(x%+'');

}

int mi(int x,int y){

    return x<y?x:y;

}

int ma(int x,int y){

    return x>y?x:y;

}

const int M=6e3+;

vector<int>g[M];

int f[M],dp[M][];

void dfs(int u){

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

        int v=g[u][i];

        dfs(v);

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

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

    }

}

int main(){

    int n=read();

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

        dp[i][]=read();

    }

    while(true){

        int x=read(),y=read();

        if(!x&&!y)

            break;

        g[y].push_back(x);

        f[x]=y;

    }

    int root=;

    while(f[root]!=)

        root=f[root];

    dfs(root);

    write(ma(dp[root][],dp[root][]));

    return ;

}