#include <stdio.h>
#include <stack>
#include <queue>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;

const int N = 500005, oo=0x3c3c3c3c;
int n, m;
int Value1[N], Value2[N];
bool Exit1[N], Exit2[N];
vector<int> a1[N], a2[N], b[N];
int Group[N];
bool Bfs[N], Dfs[N];
vector<int> List;
int F[N]; bool FF[N];

int f(int u) {
    if (FF[u]++) return F[u];
    int Max = (Exit2[u] ? 0 : -oo);
    for (int i=0; int v=b[u][i]; i++)
    Max = max(Max, f(v));
    //printf("f(%d) = %d\n", u, Max + Value2[u]);
    return F[u] = Max + Value2[u];
}

void bfs(int U) {
    queue<int> qu; 
    qu.push(U); Bfs[U]=true;
    while (qu.size()) {
        int u=qu.front(); qu.pop();
        Group[u]=U;
        //printf("%d ", u);
        for (int i=0; int v=a2[u][i]; i++)
        if (!Bfs[v]) { qu.push(v); Bfs[v]=true; }
    }
    //printf("Group=%d\n", U);
}

void dfs(int U) {
    stack<int> st; st.push(U);
    while (st.size()) {
        int u=st.top(); st.pop();
        if (u<0) {
            List.push_back(-u);
        } else if (!Dfs[u]) {
            Dfs[u] = true;
            st.push(-u);
            for (int i=0; int v=a1[u][i]; i++)
            if (!Dfs[v]) st.push(v);
        }
    }
}

main() {
    scanf("%d%d", &n, &m);
    for (int i=1; i<=m; i++) {
        int x, y; scanf("%d%d", &x, &y);
        a1[x].push_back(y);
        a2[y].push_back(x);
    }
    for (int i=1; i<=n; i++) {
        a1[i].push_back(0);
        a2[i].push_back(0);
        scanf("%d", &Value1[i]);
    }

    int S, P;
    scanf("%d%d", &S, &P);

    for (int i=1; i<=P; i++) {
        int x; scanf("%d", &x);
        Exit1[x] = true;
    }
    // done a, Value1, Exit1

    for (int i=1; i<=n; i++)
        if (!Dfs[i]) dfs(i);
    for (int i=List.size()-1; i>=0; i--)
        if (!Bfs[List[i]]) bfs(List[i]);
    // done Group, Dfs, Bfs

    for (int i=1; i<=n; i++)
    if (int I = Group[i]) {
        Value2[I] += Value1[i];
        Exit2[I] |= Exit1[i];
    }
    // done Value2, Exit2

    for (int u=1; u<=n; u++)
    if (int U=Group[u]) {
        for (int i=0; int v=a1[u][i]; i++)
        if (U!=Group[v])
        b[U].push_back(Group[v]);
    }
    for (int i=1; i<=n; i++) {
        #define all(a) a.begin(), a.end()
        sort(all(b[i]));
        b[i].erase(unique(all(b[i])), b[i].end());
        b[i].push_back(0);  
    }
    // done b

    for (int i=List.size()-1; i>=0; i--)
        f(Group[List[i]]);
    cout << f(Group[S]) << endl;
}