#include "bits/stdc++.h"
//#define int long long
using namespace std;
using ll = long long;
using P = pair<ll, ll>;
const ll INF = (1LL << 61);
ll mod = 998244353;

signed main() {
	ios::sync_with_stdio(false);
	cin.tie(0);
	int N, M; cin >> N >> M;
	vector<int>A(N); for (int i = 0; i < N; i++)cin >> A[i];
	vector<vector<int>>G(N);
	for (int i = 0; i < M; i++) {
		int u, v; cin >> u >> v; u--; v--;
		if (A[u] < A[v]) {
			G[u].push_back(v);
		}
		else if (A[u] > A[v]) {
			G[v].push_back(u);
		}
	}
	int K; cin >> K;
	vector<bool>now(N, false);
	for (int i = 0; i < K; i++) {
		int B; cin >> B; B--;
		now[B] = true;
	}
	vector<int>ans;
	vector<int>ind(N);
	for (int i = 0; i < N; i++) {
		for (auto x : G[i]) {
			ind[x]++;
		}
	}
	queue<int> que;
	for (int i = 0; i < N; i++) {  // 次数が0の点をキューに入れる
		if (ind[i] == 0) {
			que.push(i);
		}
	}
	while (!que.empty()) {  // 幅優先探索
		int t = que.front();
		ans.push_back(t);
		que.pop();
		for (auto e : G[t]) {
			ind[e]--;
			if (ind[e] == 0) {
				que.push(e);
			}
		}
	}
	if (ans.size() != N) {
		cout << -1 << endl; return 0;
	}
	int cnt = 0;
	vector<int>res;
	for (int i = 0; i < N; i++) {
		if (now[ans[i]]) {
			cnt++;
			res.push_back(ans[i] + 1);
			now[ans[i]] = false;
			for (auto v : G[ans[i]]) {
				if (now[v])now[v] = false;
				else now[v] = true;
			}
		}
	}
	cout << cnt << endl;
	for (int i = 0; i < cnt; i++) {
		cout << res[i] << endl;
	}
	return 0;
}