from collections import defaultdict, deque

n, m = map(int, input().split())
A = list(map(int, input().split()))
IN = [0 for _ in range(n)]
G = defaultdict(list)
for _ in range(m):
    u, v = map(int, input().split())
    u -= 1
    v -= 1
    if A[u] > A[v]:
        G[v].append(u)
        IN[u] += 1
    elif A[u] < A[v]:
        G[u].append(v)
        IN[v] += 1
Que = deque([(i, 0) for i in range(n) if IN[i] == 0])
k = int(input())
B = set(map(int, input().split()))
ANS = []
while Que:
    idx, on = Que.popleft()
    if idx + 1 in B:
        if on == 0:
            ANS.append(idx + 1)
            on = 1
    else:
        if on == 1:
            ANS.append(idx + 1)
            on = 0
    for nidx in G[idx]:
        Que.append((nidx, on))
print(len(ANS))
print(*ANS, sep='\n')