def main():
    from collections import defaultdict
    import heapq
    
    n, m = map(int, input().split())
    a = list(map(int, input().split()))

    adj = defaultdict(list)
    for _ in range(m):
        u, v = map(int, input().split())
        u -= 1
        v -= 1
        if a[u] < a[v]:
            adj[u].append(v)
        if a[v] < a[u]:
            adj[v].append(u)

    _ = int(input())
    b = list(map(lambda x: int(x) - 1, input().split()))
    onoff = [(i in b) for i in range(n)]

    hq = [(a[i], i) for i in b]
    heapq.heapify(hq)

    ans = []
    while hq:
        x, y = heapq.heappop(hq)
        if not onoff[y]:
            continue
        ans.append(y + 1)
        onoff[y] = False
        for v in adj[y]:
            onoff[v] = not onoff[v]
            if onoff[v]:
                heapq.heappush(hq, (a[v], v))

    print(len(ans))
    print(*ans, sep='\n')


if __name__ == "__main__":
    main()