n, m = map(int, input().split())
a = list(map(int, input().split()))
to = [[] for _ in range(n)]
for _ in range(m):
    u, v = map(int, input().split())
    u -= 1
    v -= 1
    to[u].append(v)
    to[v].append(u)
s = [False] * n
k = int(input())
for bi in map(int, input().split()):
    bi -= 1
    s[bi] = True

ans = []
for u in sorted(range(n), key=lambda i: a[i]):
    if s[u]:
        s[u] = False
        ans.append(u + 1)
        for v in to[u]:
            if a[u] < a[v]:
                s[v] = not s[v]
if any(s):
    print(-1)
else:
    print(len(ans))
    print(*ans, sep='\n')