N,M = map(int,input().split())
A = list(map(int,input().split()))
G = [[] for _ in range(N+1)]
for _ in range(M):
    u,v = map(int,input().split())
    if A[u-1] < A[v-1]:
        G[u].append(v)
    elif A[u-1] > A[v-1]:
        G[v].append(u)
K = int(input())
B = list(map(int,input().split()))
memo = [False] * (N + 1)
for b in B:
    memo[b] = True
import heapq
q = [(A[b-1],b) for b in B]
heapq.heapify(q)
ans = []
while (len(q)):
    a,b = heapq.heappop(q)
    if memo[b] == False:
        continue
    ans.append(b)
    memo[b] = False
    for v in G[b]:
        memo[v] = not memo[v]
        if memo[v]:
            heapq.heappush(q,(A[v-1],v))
print(len(ans))
for a in ans:
    print(a)