import heapq
from sys import stdin

n, m = map(int, stdin.readline().split())
a = list(map(int, stdin.readline().split()))

adj = [[] for _ in range(n)]
for _ in range(m):
    u, v = map(int, stdin.readline().split())
    u -= 1
    v -= 1
    if a[u] < a[v]:
        adj[u].append(v)
    if a[v] < a[u]:
        adj[v].append(u)

_ = int(input())
b = list(map(lambda x: int(x) - 1, stdin.readline().split()))
onoff = [(i in b) for i in range(n)]

hq = [(a[i], i) for i in b]
heapq.heapify(hq)
ans = []
while hq:
    x, y = heapq.heappop(hq)
    if not onoff[y]:
        continue
    ans.append(y + 1)
    onoff[y] = False
    for v in adj[y]:
        onoff[v] = not onoff[v]
        if onoff[v]:
            heapq.heappush(hq, (a[v], v))

print(len(ans))
print(*ans, sep='\n')