#include <bits/stdc++.h>
using namespace std;

const int N = 500005;
int n, m, s, p;
int h[N], cnt, scc_cnt, ecnt;

struct E { int v, next; } e[1000005];
struct NE { int v, w, next; } ne[5000005];

int nh[N], val[N], vis[N], dis[N];
int a[N], tar[N], dfn[N], low[N];
int idx, inst[N], sid[N];
stack<int> stk;
queue<int> q;

void add_e(int u, int v) {
    e[++cnt].v = v;
    e[cnt].next = h[u];
    h[u] = cnt;
}

void add_ne(int u, int v, int w) {
    ne[++ecnt].v = v;
    ne[ecnt].w = w;
    ne[ecnt].next = nh[u];
    nh[u] = ecnt;
}

void dfs(int u) {
    dfn[u] = low[u] = ++idx;
    stk.push(u);
    inst[u] = 1;
    
    for (int i = h[u]; i; i = e[i].next) {
        int v = e[i].v;
        if (!dfn[v]) {
            dfs(v);
            low[u] = min(low[u], low[v]);
        } else if (inst[v]) {
            low[u] = min(low[u], dfn[v]);
        }
    }
    
    if (dfn[u] == low[u]) {
        int t;
        scc_cnt++;
        do {
            t = stk.top();
            stk.pop();
            inst[t] = 0;
            sid[t] = scc_cnt;
        } while (t != u);
    }
}

int main() {
	freopen("atm.in","r",stdin);
	freopen("atm.out","w",stdout);
    scanf("%d%d", &n, &m);
    
    for (int i = 1; i <= m; i++) {
        int u, v;
        scanf("%d%d", &u, &v);
        add_e(u, v);
    }
    
    for (int i = 1; i <= n; i++) {
        scanf("%d", &a[i]);
    }
    
    scanf("%d%d", &s, &p);
    
    for (int i = 1; i <= p; i++) {
        scanf("%d", &tar[i]);
    }
    
    for (int i = 1; i <= n; i++) {
        if (!dfn[i]) {
            dfs(i);
        }
    }
    
    for (int i = 1; i <= n; i++) {
        val[sid[i]] += a[i];
    }
    
    for (int u = 1; u <= n; u++) {
        for (int i = h[u]; i; i = e[i].next) {
            int v = e[i].v;
            if (sid[u] != sid[v]) {
                add_ne(sid[u], sid[v], val[sid[v]]);
            }
        }
    }
    
    q.push(sid[s]);
    memset(dis, 0, sizeof(dis));
    dis[sid[s]] = val[sid[s]];
    vis[sid[s]] = 1;
    
    while (!q.empty()) {
        int u = q.front();
        q.pop();
        vis[u] = 0;
        
        for (int i = nh[u]; i; i = ne[i].next) {
            int v = ne[i].v;
            if (dis[v] < dis[u] + ne[i].w) {
                dis[v] = dis[u] + ne[i].w;
                if (!vis[v]) {
                    q.push(v);
                    vis[v] = 1;
                }
            }
        }
    }
    
    int res = 0;
    for (int i = 1; i <= p; i++) {
        res = max(res, dis[sid[tar[i]]]);
    }
    
    printf("%d", res);
    return 0;
}