class Peek:
    def __init__(self, i, A):
        self.i = i
        self.A = A
        self.V = []
        self.B = False
    def __str__(self):
        return str(self.i) + ":" + str(self.A) + "," + str(self.B) + "," + str(self.V)
        
N, M = map(int, input().split())

A = []
for i, a in enumerate(list(map(int, input().split()))):
    A.append(Peek(i, a))
    
for _ in range(M):
    u, v = map(int, input().split())
    A[u-1].V.append(v-1)
    A[v-1].V.append(u-1)
    
K = int(input())
for b in list(map(int, input().split())):
    A[b-1].B = True

S = sorted(A, key=lambda x: x.A)

op = []
for p in S:
    if p.B :
        p.B = False
        op.append(p.i+1)
        for i in p.V:
            if p.A < A[i].A:
                A[i].B = not A[i].B
            
if any([i.B for i in A]):
    print(-1)
else:
    print(len(op))
    for p in op:
        print(p)