#include <iostream>
#include <queue>
using namespace std;

struct Graph
{
    int n;
    std::vector<std::vector<int>> g;
    
    Graph(){}
    
    Graph(int n) : n(n){
        g.resize(n);
    }
    
    void add_edge(int from, int to){
        g[from].push_back(to);
    }
};

int main()
{
    int n, m;
    cin >> n >> m;
    int a[100005];
    for(int i = 0; i < n; i++) cin >> a[i];
    Graph g(n), r(n);
    for(int i = 0; i < m; i++){
        int u, v;
        cin >> u >> v;
        u--; v--;
        if(a[u] < a[v]){
            g.add_edge(u, v);
            r.add_edge(v, u);
        }
        if(a[u] > a[v]){
            g.add_edge(v, u);
            r.add_edge(u, v);
        }
    }
    int k;
    cin >> k;
    bool b[100005]{0};
    for(int i = 0; i < k; i++){
        int u;
        cin >> u;
        u--;
        b[u] = true;
    }
    bool c[100005]{0};
    queue<int> que;
    for(int u = 0; u < n; u++){
        if(r.g[u].size() == 0){
            c[u] = true;
            que.push(u);
        }
    }
    vector<int> ans;
    while(que.size()){
        int u = que.front();
        que.pop();
        if(b[u]) ans.push_back(u);
        for(int v : g.g[u]){
            if(b[u]) b[v] = !b[v];
            if(!c[v]){
                c[v] = true;
                que.push(v);
            }
        }
    }
    cout << (int)ans.size() << endl;
    for(int u : ans) cout << u + 1 << endl;
    cout << endl;
}