import java.io.*;
import java.util.*;
import java.util.function.*;
import java.util.stream.*;

public class Main {
    public static void main(String[] args) throws Exception {
        Scanner sc = new Scanner();
        int n = sc.nextInt();
        int m = sc.nextInt();
        List<Integer> values = Stream.generate(sc::nextInt).limit(n).toList();
        List<List<Integer>> graph = IntStream.range(0, n).mapToObj(i -> new ArrayList<Integer>()).collect(Collectors.toList());
        IntStream.range(0, m).forEach(i -> {
            int a = sc.nextInt() - 1;
            int b = sc.nextInt() - 1;
            if (values.get(a) < values.get(b)) {
                graph.get(a).add(b);
            } else if (values.get(b) < values.get(a)) {
                graph.get(b).add(a);
            }
        });
        boolean[] isOn = new boolean[n];
        IntStream.range(0, sc.nextInt()).forEach(i -> {
            isOn[sc.nextInt() - 1] = true;
        });
        List<Integer> ans = new ArrayList<>();
        IntStream.range(0, n).forEach(i -> {
            if (isOn[i]) {
                ans.add(i + 1);
                graph.get(i).stream().forEach(x -> isOn[x] ^= true);
            }
        });
        System.out.println(ans.size());
        System.out.println(ans.stream().map(x -> x.toString()).collect(Collectors.joining("\n")));
    }
}
class Scanner {
    BufferedReader br;
    StringTokenizer st = new StringTokenizer("");
    StringBuilder sb = new StringBuilder();
    
    public Scanner() {
        try {
            br = new BufferedReader(new InputStreamReader(System.in));
        } catch (Exception e) {
            
        }
    }
    
    public int nextInt() {
        return Integer.parseInt(next());
    }
    
    public long nextLong() {
        return Long.parseLong(next());
    }
    
    public double nextDouble() {
        return Double.parseDouble(next());
    }
    
    public String next() {
        try {
            while (!st.hasMoreTokens()) {
                st = new StringTokenizer(br.readLine());
            }
        } catch (Exception e) {
            e.printStackTrace();
        } finally {
            return st.nextToken();
        }
    }
    
}