import collections N, M = map(int, input().split()) A = list(map(lambda x: int(x) - 1, input().split())) G = collections.defaultdict(set) for _ in range(M): v0, v1 = map(lambda x: int(x) - 1, input().split()) # 計算量の削減 if A[v0] < A[v1]: G[v0].add(v1) else: G[v1].add(v0) K = int(input()) B = list(map(lambda x: int(x) - 1, input().split())) onoff = [int(gi in B) for gi in range(N)] greedy = [(A[ai], ai) for ai in range(N)] greedy.sort() ans = [] for a, gi in greedy: if onoff[gi] != 1: continue onoff[gi] = 0 ans.append(gi) for ri in G[gi]: if A[ri] > a: onoff[ri] ^= 1 if sum(onoff) > 0: print(-1) else: print(len(ans)) print(*map(lambda x: x + 1, ans), sep='\n')