import bisect
import copy
import decimal
import fractions
import heapq
import itertools
import math
import random
import sys
import time
from collections import Counter,deque,defaultdict
from functools import lru_cache,reduce
from heapq import heappush,heappop,heapify,heappushpop,_heappop_max,_heapify_max
def _heappush_max(heap,item):
    heap.append(item)
    heapq._siftdown_max(heap, 0, len(heap)-1)
def _heappushpop_max(heap, item):
    if heap and item < heap[0]:
        item, heap[0] = heap[0], item
        heapq._siftup_max(heap, 0)
    return item
from math import gcd as GCD
read=sys.stdin.read
readline=sys.stdin.readline
readlines=sys.stdin.readlines
write=sys.stdout.write
#import pypyjit
#pypyjit.set_param('max_unroll_recursion=-1')
#sys.set_int_max_str_digits(10**9)

N,M=map(int,readline().split())
A=list(map(int,readline().split()))
graph=[[] for x in range(N)]
for m in range(M):
    u,v=map(int,readline().split())
    u-=1;v-=1
    if A[u]>A[v]:
        u,v=v,u
    graph[u].append(v)
dp=[0]*N
ans_lst=[]
K=int(readline())
for b in map(int,readline().split()):
    b-=1
    dp[b]=1
for x in sorted([x for x in range(N)],key=lambda x:A[x]):
    if dp[x]:
        dp[x]^=1
        for y in graph[x]:
            dp[y]^=1
        ans_lst.append(x)
if all(dp[x]==0 for x in range(N)):
    print(len(ans_lst))
    for m in ans_lst:
        print(m+1)
else:
    print(-1)