import heapq
n,m=map(int,input().split())
a=list(map(int,input().split()))
g=[[] for _ in range(n)]
for _ in range(m):
    u,v=map(int,input().split())
    u-=1;v-=1
    if a[u]<a[v]:
        g[u].append(v)
    if a[u]>a[v]:
        g[v].append(u)
k=int(input())
b=list(map(int,input().split()))
memo=[0]*n
for i in b:
    memo[i-1]=1
q=[(a[i-1],i-1) for i in b]
heapq.heapify(q)
ans=[]
while q:
    num,now=heapq.heappop(q)
    if memo[now]==0:
        continue
    ans.append(now)
    memo[now]=0
    for to in g[now]:
        memo[to]=1-memo[to]
        if memo[to]:
            heapq.heappush(q,(a[to],to))
print(len(ans))
for i in ans:
    print(i+1)