#include<cstdio>
#include<cctype>
#include<vector>
#include<algorithm>
using namespace std;
inline int read(){
    char c; while(c=getchar(),!isdigit(c)); int x=c-‘0‘;
    while(c=getchar(),isdigit(c)) x=x*10+c-‘0‘; return x;
}
const int maxn=500001;
vector<int> e[maxn],e_[maxn];
int n,m,yes[maxn],vis[maxn],val[maxn],v[maxn],scc,f[500001],low[500001],dfn[500001],s[500001],tme,top;
void tarjan(int o){
    s[++top]=o;
    low[o]=dfn[o]=++tme;
    for(int i=0;i<e[o].size();i+=1)
        if(!vis[e[o][i]]){
            if(!low[e[o][i]]) tarjan(e[o][i]);
            low[o]=min(low[e[o][i]],low[o]);
        }
    if(dfn[o]==low[o]){
        ++scc;
        do{
            vis[s[top]]=scc;
            val[scc]+=v[s[top]];
        }while(s[top--]!=o);
    }
}
void tarjan_work(){
    for(int i=1;i<=n;i+=1) if(!low[i]) tarjan(i);
    for(int i=1;i<=n;i+=1)
        for(int j=0;j<e[i].size();j+=1)
            if(vis[i]!=vis[e[i][j]])
                e_[vis[i]].push_back(vis[e[i][j]]);
     
}
int dfs(int o){
    if(f[o]) return yes[o];
    f[o]=val[o];
    for(int i=0;i<e_[o].size();i+=1)
        if(dfs(e_[o][i]))
            yes[o]=1,f[o]=max(f[e_[o][i]]+val[o],f[o]);
    return yes[o];
}
int main(){
    n=read(),m=read();
    while(m--){
        int u=read(),v=read();
        e[u].push_back(v);
    }
    for(int i=1;i<=n;i+=1) v[i]=read();
    tarjan_work();
    int s=read(),p=read();
    while(p--){
        int x=read();
        yes[vis[x]]=1;
    }
    dfs(vis[s]);
    printf("%d\n",f[vis[s]]);
    return 0;
}