#include<bits/stdc++.h>
using namespace std;
#define int  long long
#define kg putchar(' ')
#define endl puts("")
inline int read(){
    int vis=1,ans=0;
    char x=getchar();
    while(x<'0'||x>'9'){
        if(x=='-')vis=-1;
        x=getchar();
    }
    while(x>='0'&&x<='9'){
        ans=ans*10+x-'0';
        x=getchar();
    }
    return vis*ans;
}
inline void print(int x){
    if(x<0)putchar('-'),x=-x;
    if(x>9)print(x/10);
    putchar(x%10+'0');
}
const int N=5e5+9,M=5e5+9;
struct node{
	int nxt,to;
}e[M];
int head[N],cnt;
inline void add(int x,int y){
	++cnt;
	e[cnt].to=y;
	e[cnt].nxt=head[x];
	head[x]=cnt;
}
struct edge{
	int nxt,to;
}de[M];
int headde[N],tot;
inline void addd(int x,int y){
	++tot;
	de[tot].to=y;
	de[tot].nxt=headde[x];
	headde[x]=tot;
}
int n=read(),m=read(),u,v;
int dfn[N],low[N],tmp,f[N],vis[N],team[N],num[N],teamnum,d[N];
stack<int>s;
inline void modify(int x){
	s.pop();
	team[x]=teamnum;
	num[teamnum]++;
	vis[x]=0;
} 
inline void taijian(int x){
	dfn[x]=low[x]=++tmp;
	f[x]=1;
	s.push(x);
	vis[x]=1;
	for(int i=head[x];i;i=e[i].nxt){
		int y=e[i].to;
		if(!dfn[y]){
			taijian(y);
			low[x]=min(low[x],low[y]);
		}
		else if(vis[y])low[x]=min(low[x],dfn[y]);
	}
	if(low[x]==dfn[x]){
		teamnum++;
		while(s.top()!=x){
			int t=s.top();
			modify(t);
		}
		modify(x);
	}
}
int rd[N];
inline void build(){
	for(int i=1;i<=n;i++){
		if(!f[i])continue;
		for(int j=head[i];j;j=e[j].nxt){
			if(team[i]==team[e[j].to])continue;
			addd(team[i],team[e[j].to]);
			rd[team[j]]++;
		}
	}
}
int dp[N];
int a[N];
int S;
queue<int>q; 
int ans;
inline void DP(){
	dp[team[S]]=a[team[S]];
	q.push(team[S]);
	while(!q.empty()){
		u=q.front();
		q.pop();
		for(int i=headde[u];i;i=de[i].nxt){
			v=de[i].to;
			dp[v]=max(dp[v],dp[u]+a[v]);
			if(!(--rd[v]))q.push(v);
		}
	}
}
int B[N],uiu;
signed main(){
	for(int i=1;i<=m;i++){
		u=read(),v=read();
		add(u,v);
	}
	for(int i=1;i<=n;i++){
		a[i]=read();
	}
	S=read();
	taijian(S);
	for(int i=1;i<=n;i++){
		B[team[i]]+=a[i];
	}
	for(int i=1;i<=teamnum;i++){
		a[i]=B[i];
	}
	build();
	DP();
	int P=read();
	for(int i=1;i<=P;i++){
		u=read();
		ans=max(ans,dp[team[u]]);
	}
//	for(int i=1;i<=teamnum;i++)print(dp[i]),kg;
	print(ans);
    return 0;
}