#include <bits/stdc++.h>
using namespace std;

using ll = long long;

#define rep(i, n) for (int i=0; i<(int)(n); ++(i))
#define rep3(i, m, n) for (int i=(m); (i)<(int)(n); ++(i))
#define repr(i, n) for (int i=(int)(n)-1; (i)>=0; --(i))
#define rep3r(i, m, n) for (int i=(int)(n)-1; (i)>=(int)(m); --(i))
#define all(x) (x).begin(), (x).end()

int main() {
	int n, m, k;
	cin >> n >> m;
	vector<int> a(n);
	map<int, vector<int>> aval;
	rep(i, n) {
		cin >> a[i];
		aval[a[i]].push_back(i);
	}
	vector<vector<int>> g(n);
	rep(i, m) {
		int ui, vi;
		cin >> ui >> vi;
		--ui; --vi;
		g[ui].push_back(vi);
		g[vi].push_back(ui);
	}
	cin >> k;
	vector<bool> sw(n);
	rep(i, k) {
		int bi;
		cin >> bi;
		--bi;
		sw[bi] = true;
	}
	vector<int> res;
	for (auto p : aval) {
		rep(i, (int)(p.second.size())) {
			if (sw[p.second[i]]) {
				res.push_back(p.second[i]+1);
				sw[p.second[i]] = false;
				rep(j, (int)(g[p.second[i]].size())) if (a[g[p.second[i]][j]] > a[p.second[i]]) {
					sw[g[p.second[i]][j]] = (!sw[g[p.second[i]][j]]);
				}
			}
		}
	}
	bool ok = true;
	rep(i, n) if (sw[i]) ok = false;
	if (ok) {
		cout << (int)(res.size()) << endl;
		rep(i, (int)(res.size())) cout << res[i] << endl;
	}
	else cout << -1 << endl;
	return 0;
}