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].append(b)
    else:
        if A[b] < A[a]:
            X[b].append(a)

for j in range(len(B)):
    L[B[j]-1] = 1

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

Y = []
D = 0

while sum(L) > 0:
    if D == N:
        break
    if L[C[D]] == 0:
        D += 1
    else:
        L[C[D]] = 0
        Y.append(C[D]+1)
        for i, item in enumerate(X[C[D]][1:]):
            L[item] = (L[item]+1)%2
        D += 1

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