import sys
from collections import deque

data = input().split()[1:]
rule = input().split()[1:]
# print(rule)
# 先处理规则
rs = list(set(rule))
rs.sort(key=lambda x:int(x))
# print(rs)
res = deque()
for r in rs:
    res_temp = deque()
    cnt = 0
    for idx , d in enumerate(data):
        if r in d:
            cnt+=1
            res_temp.extend([idx,d])
    if cnt:
        res_temp.appendleft(cnt)
        res_temp.appendleft(r)
        res.extend(res_temp)
l = len(res)
res.appendleft(l)
print(*list(res))