N, M = map(int, input().split())
A = [int(s) for s in input().split()]
V = [[int(i)-1 for i in input().split()] for m in range(M)]

K = int(input())
B = [int(s) for s in input().split()]

X = [0]*N

for i in range(N):
    X[i] = [0]*N

L = [0]*N

for i in range(M):
    a = V[i][0]
    b = V[i][1]
    if A[a] < A[b]:
        X[a][b] = 1
    else:
        if A[b] < A[a]:
            X[b][a] = 1

for i in range(K):
    L[B[i]-1] = 1

_, C = (list(t) for t in zip(*sorted(zip(A, list(range(N))))))

Y = [0]*N
D = 0

S = 0

del A, B, V, K
while sum(L) > 0:
    if D == N:
        break
    E = C[D]
    if L[E] == 0:
        D += 1
    else:
        L[E] = 0
        Y[S]=E+1
        for i in range(N):
            if X[E][i] == 1:
                L[i] = (L[i]+1)%2
        D += 1
        S += 1

if D == N+1:
    print(-1)
else:
    print(S)
    for i in range(S):
        print(Y[i])