(n, m) = map(int, input().split())
a = list(map(int, input().split()))
graph = [[] for _ in range(n)]

for _ in range(m):
    (u, v) = map(int, input().split())
    u -= 1
    v -= 1
    graph[u].append(v)
    graph[v].append(u)

_ = input()
b = list(map(int, input().split()))
on = [False] * n

for bi in b:
    on[bi - 1] = True

indice = [(ai, index) for ai, index in zip(a, range(n))]
indice.sort()

results = []

for (ai, index) in indice:
    if on[index]:
        on[index] = False
        results.append(index + 1)
        for v in graph[index]:
            if a[index] < a[v]:
                on[v] ^= True

if any(on):
    print(-1)
else:
    print(len(results))
    for res in results:
        print(res)