# a昇順で頂点を見ていく
# スイッチついていたら消す、そのときに連鎖先もスイッチ押す

N, M = map(int, input().split())
A = list(map(int, input().split()))
edges = [[] for i in range(N)]
for i in range(M):
    u, v = map(int, input().split())
    edges[u-1].append(v-1)
    edges[v-1].append(u-1)
K = int(input())
B = list(map(int, input().split()))
switch = [0]*N
for b in B:
    switch[b-1] = 1

A_idx = []
for i in range(N):
    A_idx.append((A[i], i))
A_idx.sort()
    
from collections import deque
que = deque(A_idx)
#visited = [0]*N
ans_list = []
while que:
    ca, ci = que.popleft()
    if switch[ci] == 1:
        ans_list.append(ci)
        for nxt in edges[ci]:
            if A[nxt] > A[ci]:
                switch[nxt] ^= 1
print(len(ans_list))
for a in ans_list:
    print(a+1)