n,m = map(int,input().split())
*a, = 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[v] < a[u]:
        g[v].append(u)
res = [0]*n
_ = input()
for i in map(int,input().split()):
    res[i-1] = 1
ans = []
for v in sorted(range(n), key=lambda i:a[i]):
    if res[v]:
        res[v] = 0
        ans.append(v+1)
        for c in g[v]:
            res[c] ^= 1
if sum(res):
    print(-1)
else:
    print(len(ans))
    print(*ans,sep="\n")