#include<cstdio>

#include<cctype>

#include<cstring>

inline long long read(){

    long long num=,f=;

    char ch=getchar();

    while(!isdigit(ch)){

        if(ch=='-')    f=-;

        ch=getchar();

    }

    while(isdigit(ch)){

        num=num*+ch-'';

        ch=getchar();

    }

    return num*f;

}

inline long long max(long long a,long long b){    return a>b?a:b;    }

inline long long min(long long a,long long b){    return a<b?a:b;    }

struct Edge{

    int next,to;

};

struct Pic{

    Edge edge[];

    int head[],num;

    inline void add(int from,int to){

        edge[++num]=(Edge){head[from],to};

        head[from]=num;

    }

}Old,New;

int que[];

int fsh[];

int f[],h,t=;

int stack[],top;

int dfn[],low[],ID;

int col[],cnt;

int val[];

bool vis[];

int dis[];

void tarjan(int x){

    vis[x]=;

    dfn[x]=low[x]=++ID;

    stack[++top]=x;

    for(int i=Old.head[x];i;i=Old.edge[i].next){

        int to=Old.edge[i].to;

        if(!dfn[to]){

            tarjan(to);

            low[x]=min(low[x],low[to]);

        }

        else if(vis[to])    low[x]=min(low[x],dfn[to]);

    }

    if(dfn[x]==low[x]){

        vis[x]=;

        col[x]=++cnt;

        val[cnt]+=que[x];

        while(stack[top]!=x){

            vis[stack[top]]=;

            val[cnt]+=que[stack[top]];

            col[stack[top--]]=cnt;

        }

        top--;

    }

}

int ans;

int main(){

    int n=read(),m=read();

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

        int from=read(),to=read();

        Old.add(from,to);

    }

    for(int i=;i<=n;++i)    que[i]=read();

    int s=read(),p=read();

    for(int i=;i<=p;++i)     fsh[i]=read();

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

        if(!dfn[i])    tarjan(i);

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

        for(int j=Old.head[i];j;j=Old.edge[j].next){

            int to=Old.edge[j].to;

            if(col[i]!=col[to])    New.add(col[i],col[to]);

        }

    f[]=col[s];

    memset(vis,,sizeof(vis));

    dis[col[s]]=val[col[s]];

    while(h<t){

        h++;

        int from=f[h];

        vis[from]=;

        for(int i=New.head[from];i;i=New.edge[i].next){

            int to=New.edge[i].to;

            if(dis[to]<dis[from]+val[to]){

                dis[to]=dis[from]+val[to];

                if(!vis[to]){

                    vis[to]=;

                    f[++t]=to;

                }

            }

        }

    }

    for(int i=;i<=p;++i)    ans=max(ans,dis[col[fsh[i]]]);

    printf("%d",ans);

    return ;

}