import sys
import pypyjit
import itertools
import heapq
import math
from collections import deque, defaultdict
import bisect

input = sys.stdin.readline
sys.setrecursionlimit(10 ** 6)
pypyjit.set_param('max_unroll_recursion=-1')


def index_lt(a, x):
    'return largest index s.t. A[i] < x or -1 if it does not exist'
    return bisect.bisect_left(a, x) - 1


def index_le(a, x):
    'return largest index s.t. A[i] <= x or -1 if it does not exist'
    return bisect.bisect_right(a, x) - 1


def index_gt(a, x):
    'return smallest index s.t. A[i] > x or len(a) if it does not exist'
    return bisect.bisect_right(a, x)


def index_ge(a, x):
    'return smallest index s.t. A[i] >= x or len(a) if it does not exist'
    return bisect.bisect_left(a, x)


class TopologicalSort():
    def __init__(self, N, E, D):
        self.N = N
        self.E = E
        self.D = D

    def sort(self):
        dq = deque([])
        for i in range(self.N):
            if self.D[i] == 0:
                dq.append(i)
        if len(dq) == 0:
            return False, None

        ret = []
        while len(dq) > 0:
            v = dq.popleft()
            ret.append(v)
            for dest in self.E[v]:
                self.D[dest] -= 1
                if self.D[dest] == 0:
                    dq.append(dest)

        for i in range(self.N):
            if not self.D[i] == 0:
                return False, None
        return True, ret


N, M = map(int, input().split())
A = list(map(int, input().split()))
E = [[] for _ in range(N)]
D = [0] * N
for _ in range(M):
    u, v = map(int, input().split())
    u -= 1
    v -= 1
    if A[u] == A[v]:
        continue
    if A[u] > A[v]:
        u, v = v, u
    E[u].append(v)
    D[v] += 1

K = int(input())
B = list(map(lambda x: int(x) - 1, input().split()))
lamp = [False] * (N)
for b in B:
    lamp[b] = True

success, V = TopologicalSort(N, E, D).sort()
assert success is True

ans = []
for v in V:
    if lamp[v] is True:
        lamp[v] = False
        ans.append(v + 1)
        for d in E[v]:
            lamp[d] = not lamp[d]
print(len(ans))
print(*ans, sep='\n')