from sys import stdin, setrecursionlimit
setrecursionlimit(10**7)
N,M = map(int,input().split())
A = list(map(int,input().split()))
l = [[] for _ in range(N)]
for _ in range(M):
    a,b = map(int,input().split())
    a -= 1
    b -= 1
    if A[a] < A[b]:
        l[a].append(b)
    if A[b] < A[a]:
        l[b].append(a)
K = int(input())
B = list(map(int,input().split()))
lamps = [0]*N
for b in B:
    lamps[b-1] = 1
dag = [0]*N
for i in range(N):
    for j in l[i]:
        dag[j] += 1
que, dir = [], []
for i in range(N):
    if dag[i] == 0:
        que.append(i)
while que:
    cursor = que.pop()
    if lamps[cursor] == 1:
        dir.append(cursor)
        for nextCursor in l[cursor]:
            lamps[nextCursor] ^= 1
    for nextCursor in l[cursor]:
        dag[nextCursor] -= 1
        if dag[nextCursor] == 0:
            que.append(nextCursor)
print(len(dir))
for d in dir:
    print(d+1)