#include<bits/stdc++.h>
#include<iostream>
using namespace std;
using LL = long long;
using P = pair<int,int>;
using Graph = vector<vector<int>>;
const int INF = 1 << 29;
const long long LINF = 1LL << 60;
#define all(x) (x).begin(), (x).end()
#define rep(i,n) for(int i = 0; i < (n); ++i)
template<class T>void chmin(T&a, T b){if(a > b) a = b;}
template<class T>void chmax(T&a, T b){if(a < b) a = b;}


int main(){
	int N, M; cin >> N >> M;
	vector<P> A(N);
	vector<int> points(N);
	for(int i = 0; i < N; ++i){
		int tmp; cin >> tmp;
		points[i] = tmp;
		A[i] = make_pair(tmp, i);
	}
	sort(A.begin(), A.end());
	Graph G(N);
	for(int i = 0; i < M; ++i){
		int u, v; cin >> u >> v;
		--u; --v;
		G[u].push_back(v);
		G[v].push_back(u);
	}
	vector<bool> state(N, false);
	int K; cin >> K;
	for(int i = 0; i < K; ++i){
		int tmp; cin >> tmp; state[tmp-1] = true;
	}
	vector<int> ans;
	for(int i = 0; i < N; ++i){
		int now_point = A[i].first;
		int now_num = A[i].second;
		if(state[now_num]){
			ans.push_back(now_num);
			state[now_num] = false;
			for(auto next_num : G[now_num]){
				int next_point = points[next_num];
				if(now_point < next_point){
					if(state[next_num]) state[next_num] = false;
					else state[next_num] = true;
				}
			}
		}
	}
	for(auto b : state) if(b == true) {cout << -1 << endl; return 0;}
	cout << ans.size() << endl;
	for(auto v : ans) cout << v+1 << endl;

}