#include <cstdio>
#include <cstring>
#include <cmath>
#include <string>
#include <iostream>
#include <algorithm>
#include <queue>
#include <set>
#include <map>
using namespace std;
typedef long long ll;
#define rep(i, n) for(int i=0; i<(n); ++i)
#define for1(i,a,n) for(int i=(a);i<=(n);++i)
#define for2(i,a,n) for(int i=(a);i<(n);++i)
#define for3(i,a,n) for(int i=(a);i>=(n);--i)
#define for4(i,a,n) for(int i=(a);i>(n);--i)
#define CC(i,a) memset(i,a,sizeof(i))
#define read(a) a=getint()
#define print(a) printf("%d", a)
#define dbg(x) cout << (#x) << " = " << (x) << endl
#define error(x) (!(x)?puts("error"):0)
#define rdm(x, i) for(int i=ihead[x]; i; i=e[i].next)
inline const int getint() { int r=0, k=1; char c=getchar(); for(; c<'0'||c>'9'; c=getchar()) if(c=='-') k=-1; for(; c>='0'&&c<='9'; c=getchar()) r=r*10+c-'0'; return k*r; }

const int N=1000005, oo=~0u>>1;

int FF[N], LL[N], scc, p[N], vis[N], s[N], top, tot, d[N];
struct GR {
	int ihead[N], cnt, n, w[N];
	struct dat { int to, next; }e[N];
	void add(int u, int v) {
		e[++cnt].next=ihead[u]; ihead[u]=cnt; e[cnt].to=v;
	}
	void tarjan(int x) {
		FF[x]=LL[x]=++tot; vis[x]=1; s[++top]=x;
		int y;
		rdm(x, i) {
			y=e[i].to;
			if(!FF[y]) tarjan(y), LL[x]=min(LL[x], LL[y]);
			else if(vis[y]) LL[x]=min(LL[x], FF[y]);
		}
		if(LL[x]==FF[x]) {
			++scc;
			do {
				y=s[top--];
				vis[y]=0;
				p[y]=scc;
			} while(x!=y);
		}
	}
	void tarjan() { for1(i, 1, n) if(!FF[i]) tarjan(i); }
	void spfa(int x) {
		for1(i, 1, n) d[i]=-oo, vis[i]=0;
		d[x]=w[x]; vis[x]=1;
		int front, tail; front=tail=0;
		int *q=s;
		q[tail++]=x;
		while(front!=tail) {
			int u=q[front++], v; if(front==N) front=0; vis[u]=0;
			rdm(u, i) if(d[e[i].to]<d[u]+w[e[i].to]) {
				v=e[i].to;
				d[v]=d[u]+w[v];
				if(!vis[v]) {
					vis[v]=1;
					if(d[q[front]]<d[v]) {
						--front; if(front<0) front+=N;
						q[front]=v;
					}
					else {
						q[tail++]=v; if(tail==N) tail=0;
					}
				}
			}
		}
	}
}G, g;

void build() {
	G.tarjan();
	g.n=scc;
	for1(i, 1, G.n) g.w[p[i]]+=G.w[i];
	for1(x, 1, G.n) for(int i=G.ihead[x]; i; i=G.e[i].next) if(p[x]!=p[G.e[i].to]) g.add(p[x], p[G.e[i].to]);
}

int n, m, ans, num, bar[N];
int main() {
	read(n); read(m); G.n=n;
	for1(i, 1, m) { int u=getint(), v=getint(); G.add(u, v); }
	for1(i, 1, n) read(G.w[i]);
	int s=getint(); read(num);
	build();
	g.spfa(p[s]);
	for1(i, 1, num) read(bar[i]);
	for1(i, 1, num) ans=max(ans, d[p[bar[i]]]);
	printf("%d\n", ans);
	return 0;
}