#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<int> A(N, 0);
	for(int i = 0; i < N; ++i) cin >> A[i];
	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);
	}
	int K; cin >> K;
	vector<bool> state_off(N, true);
	for(int i = 0; i < K; ++i){
		int B; cin >> B; --B;
		state_off[B] = false;
	}
	vector<int>  ans_off;
	for(int i = 0; i < N; ++i){
		if(state_off[i]==false){
			state_off[i] = true;
			ans_off.push_back(i);
			for(auto v : G[i]){
				if(A[i]<A[v]) state_off[v] = true;
			}
		}
	}
	if(ans_off.size()==0) cout << -1 << endl;
	else{
		cout << ans_off.size() << endl;
		for(auto v : ans_off){
			cout << v+1 << endl;
		}
	}
}