#include <stdio.h>

typedef struct List {
	struct List *next;
	int v;
} list;

typedef struct {
	int key, id;
} data;

void merge_sort(data x[], int n)
{
	static data y[100001] = {};
	if (n <= 1) return;
	merge_sort(&(x[0]), n/2);
	merge_sort(&(x[n/2]), (n+1)/2);
	
	int i, p, q;
	for (i = 0, p = 0, q = n/2; i < n; i++) {
		if (p >= n/2) y[i] = x[q++];
		else if (q >= n) y[i] = x[p++];
		else y[i] = (x[p].key < x[q].key)? x[p++]: x[q++];
	}
	for (i = 0; i < n; i++) x[i] = y[i];
}

int main()
{
	int i, N, M, K, u, w, b, A[100001], B[100001] = {};
	list *adj[100001] = {}, e[200001], *p;
	data d[100001];
	scanf("%d %d", &N, &M);
	for (i = 1; i <= N; i++) {
		scanf("%d", &(A[i]));
		d[i-1].key = A[i];
		d[i-1].id = i;
	}
	merge_sort(d, N);
	for (i = 0; i < M; i++) {
		scanf("%d %d", &u, &w);
		e[i*2].v = w;
		e[i*2+1].v = u;
		e[i*2].next = adj[u];
		e[i*2+1].next = adj[w];
		adj[u] = &(e[i*2]);
		adj[w] = &(e[i*2+1]);
	}
	scanf("%d", &K);
	for (i = 1; i <= K; i++) {
		scanf("%d", &b);
		B[b] = 1;
	}
	
	int k, ans[100001];
	for (i = 0, k = 0; i < N; i++) {
		u = d[i].id;
		if (B[u] == 0) continue;
		
		B[u] = 0;
		ans[k++] = u;
		for (p = adj[u]; p != NULL; p = p->next) {
			w = p->v;
			if (A[w] > A[u]) B[w] ^= 1;
		}
	}
	for (i = 1; i <= N; i++) if (B[i] == 1) break;
	if (i <= N) printf("-1\n");
	else for (i = 0, printf("%d\n", k); i < k; i++) printf("%d\n", ans[i]);
	fflush(stdout);
	return 0;
}