/* -*- coding: utf-8 -*-
 *
 * 1477.cc:  No.1477 Lamps on Graph - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

const int MAX_N = 100000;

/* typedef */

typedef vector<int> vi;
typedef queue<int> qi;

/* global variables */

int as[MAX_N], pns[MAX_N], xs[MAX_N];
vi nbrs[MAX_N];
bool ls[MAX_N];

/* subroutines */

/* main */

int main() {
  int n, m;
  scanf("%d%d", &n, &m);

  for (int i = 0; i < n; i++) scanf("%d", as + i);

  for (int i = 0; i < m; i++) {
    int u, v;
    scanf("%d%d", &u, &v);
    u--, v--;
    if (as[u] < as[v]) nbrs[u].push_back(v), pns[v]++;
    else if (as[u] > as[v]) nbrs[v].push_back(u), pns[u]++;
  }

  int k;
  scanf("%d", &k);
  for (int i = 0; i < k; i++) {
    int bi;
    scanf("%d", &bi);
    bi--;
    ls[bi] = true;
  }

  qi q;
  for (int i = 0; i < n; i++)
    if (pns[i] == 0) q.push(i);

  int xn = 0;
  while (! q.empty()) {
    int u = q.front(); q.pop();
    if (ls[u]) xs[xn++] = u;

    vi &nbru = nbrs[u];
    for (vi::iterator vit = nbru.begin(); vit != nbru.end(); vit++) {
      int v = *vit;
      ls[v] ^= ls[u];
      if (--pns[v] == 0) q.push(v);
    }
  }

  printf("%d\n", xn);
  for (int i = 0; i < xn; i++) printf("%d\n", xs[i] + 1);
  return 0;
}