// luogu-judger-enable-o2
// luogu-judger-enable-o2
#include<cstdio>
#include<stack>
#include<cstring>
#include<algorithm>
#include<queue>
#define Pair pair<int,int>
#define F first
#define S second
using namespace std;
const int MAXN=1e6+10;
inline int read()
{
    char c=getchar();int x=0,f=1;
    while(c<'0'||c>'9'){if(c=='-')f=-1;c=getchar();}
    while(c>='0'&&c<='9'){x=x*10+c-'0';c=getchar();}
    return x*f;
}
struct node
{
    int u,v,w,nxt;
}E[MAXN],edge[MAXN];
int headE[MAXN],numE=1,head[MAXN],num=1;
inline void add_edge(int x,int y)
{
    E[numE].u=x;
    E[numE].v=y;
    E[numE].nxt=headE[x];
    headE[x]=numE++;
}
inline void AddEdge(int x,int y,int z)
{
    edge[num].u=x;
    edge[num].v=y;
    edge[num].w=z;
    edge[num].nxt=head[x];
    head[x]=num++;
}
int N,M,S,P;
int money[MAXN],pos[MAXN],sum[MAXN];
int vis[MAXN],dfn[MAXN],low[MAXN],color[MAXN],colornum=0,tot=0;
stack<int>s;
void tarjan(int now)
{
    dfn[now]=low[now]=++tot;
    s.push(now);
    vis[now]=1;
    for(int i=headE[now];i!=-1;i=E[i].nxt)
    {
        if(!dfn[E[i].v]) 
            tarjan(E[i].v),low[now]=min(low[now],low[E[i].v]);
        else if(vis[E[i].v]) 
            low[now]=min(low[now],dfn[E[i].v]);
    }
    if(low[now]==dfn[now])
    {
        int h;
        colornum++;
        do
        {
            h=s.top();
            color[h]=colornum;
            sum[colornum]+=money[h];
            vis[h]=0;
            s.pop();
            
        }while(h!=now);
    }
}
int dis[MAXN];
void Dijstra()
{
    memset(dis,0,sizeof(dis));dis[color[S]]=sum[color[S]];
    memset(vis,0,sizeof(vis));vis[color[S]]=1;
    queue<int>q;
    q.push(color[S]);
    while(q.size()!=0)
    {
        int p=q.front();q.pop();
        vis[p]=0;
        for(int i=head[p];i!=-1;i=edge[i].nxt)
        {
            if(dis[edge[i].v]<dis[p]+edge[i].w)
            {
                dis[edge[i].v]=dis[p]+edge[i].w;
                if(vis[edge[i].v]==0)
                    vis[edge[i].v]=1,q.push(edge[i].v);
            }
        }
    }
    int ans=0;
    for(int i=1;i<=P;i++)
        ans=max(ans,dis[color[pos[i]]]);
    printf("%d",ans);
}
int main()
{
    #ifdef WIN32
    freopen("a.in","r",stdin);
 //   freopen("a.out","w",stdout);
    #else
    #endif
    memset(head,-1,sizeof(head));
    memset(headE,-1,sizeof(headE));
    N=read();M=read();
    for(int i=1;i<=M;i++)
    {
        int x=read(),y=read();
        add_edge(x,y);
    }
    for(int i=1;i<=N;i++) money[i]=read();
    S=read();P=read();
    for(int i=1;i<=P;i++) pos[i]=read(); 
    for(int i=1;i<=N;i++)
        if(!dfn[i]) 
            tarjan(i);
    for(int i=1;i<=numE-1;i++)
        if(color[E[i].u]!=color[E[i].v])    
            AddEdge(color[E[i].u],color[E[i].v],sum[color[E[i].v]]);
    Dijstra();
    return 0;
}